I have put together a list of modern English words which used to be conjugated strongly. Some of them still are, but the majority have been replaced with weak forms of the verb. I have bolded obsolete or archaic forms for emphasis. In many cases I have modernized the spelling to reflect how these words would be pronounced or spelled today had they stayed strong. Strong verbs are grouped into seven classes based on the way they're conjugated (or used to be conjugated in older Germanic languages). I have tried to follow that classification. I present each verb with three conjugations: infinitive—past tense—past participle (with variations in parentheses). I've also included the different patterns (given with IPA symbols) I've noticed for different subclasses. I've also indicated irregular verbs that belong to a particular class or subclass.
DISCLAIMER: I am not a trained linguist nor have I made an extensive study of strong verbs. The following list is almost certain to have errors. If you notice any problems or know of a strong verb I've missed, feel free to comment and correct me on any point.
Pattern: /aɪ/ → /oʊ/ (or /ɪ/) → /ɪ/ + /-ən/
- abide—abode (or abid)—abidden
- arise—arose (or aras)—arisen
- bide—bode (or bid)—bidden
- bite—bote (or bat or bit)—bitten
- chide—chode (or chid)—chidden
- drive—drove (or drav or drave)—driven
- glide—glode (or glad)—glidden
- grip (gripe in Middle English)—grope (or grap or grip)—grippen
- reap (ripe in Middle English)—rope—rippen
- ride—rode (or rad or rid)—ridden
- rise—rose (or ras)—risen
- rive—rove (or rav)—riven
- shine—shone (or shan)—shinnen
- sigh (sike in Middle English)—soke—sicken
- slide—slode (or slid)—slidden
- slit (slite in Middle English)—slote (or slit)—slitten
- smite—smote (or smit)—smitten
- stride—strode (or strid)—stridden
- strike—stroke (or struck)—stricken
- thrive—throve (or thriv)—thriven
- write—wrote (or wrat or writ)—written
- yawn (yine in Middle English)—yone—yinen
- prick (prike in Middle English)—preck or preke—pricken
Pattern: /i/ → /oʊ/ (or /ɛ/) → /oʊ/ + /-ən/
- cleave—clove (or clave or clev)—cloven 
- creep—crope (or crep)—cropen
- float (fleet in Middle English)—flote (or flet)—floten
- freeze—froze (or frez)—frozen (or frorn or froren)
- lose (leese in Middle English)—lose  (or las)—lorn 
- rot (reet in Middle English)—rote (or rot)—roten (or rotten)
- seethe—sothe (or sed or sod)—sodden
- smoke (smeek in Middle English)—smoke—smoken
- sprout (spreet in Middle English)—sprote—sproten
- lock (luck in Middle English)—loke (or leck)—loken
- shove—shove  (or shev)—shoven
- choose—chose (or chas)—chosen (or coren)
- strew—strow—strown (or strewn)
- bow—bew—bowen (or bewn)
- (to tell a) lie—lee—lien
Pattern: /aɪ/ → /aʊ/ (or /æ/) → /aʊ/ (or /ʌ/) + /-ən/
- bind—bound (or band)—bounden (or bunden)
- find—found (or fand)—founden (or funden)
- grind—ground (or grand)—grounden (or grunden)
- wind—wound (or wand)—wounden (or wunden)
- fight—fought (or feght)—foughten
Pattern: /ɪ/ → /æ/ → /ʌ/ [+ /-ən/]
- begin—began—begun (or begunnen) 
- cram (crim in Middle English)—cram—crummen
- (to be) grim —gram—grummen
- run (rin in Middle English)—ran—run (or runnen) 
- spin—span—spun (or spunnen)
- swim—swam—swum (or swummen)
- tind —tand—tund
- cringe (cring in Middle English)—crang—crung
- drink—drank—drunk (or drunken)
- shrink—shrank—shrunk (or shrunken)
- sing—sang—sung (or sungen) 
- sink—sank—sunk (or sunken)
- spring—sprang—sprung (or sprungen)
- stink—stank (or stonk)—stunk
- swing—swang—swung (or swungen) 
- throng (thring in Middle English)—thrang—thrungen
- wink—wank (or wonk)—wunk
- wring—wrang—wrung (or wrungen)
- bellow (bell in Middle English)—ball—bollen
- help—halp (or holp)—holpen
- melt—malt (or molt)—molten
- milk (melk in Middle English)—malk—molken
- swallow (swellow in Middle English)—swallow—swollowen
- swell—swall (or swoll)—swollen
- swelter (swelt in Middle English)—swalt—swolten
- drop—drap (or drope)—droppen
- warp (werp in Middle English)—wurp—worpen
- yield—yald (or yeld or yold)—yolden
- carve—corve—corven (or carven)
- starve—storve—storven (or starven)
- burn—barn—bornen (or burnen)
- burst—barst (or brast)—borsten (or bursten)
- mourn—marn—mornen (or murnen)
- climb—clomb (or clamb)—clumben (or clomben) Pattern: /aɪ/ → /oʊ/ → /ʌ/ + /-ən/
- thrash/thresh—throsh—throshen Pattern: /ɛ/ or /æ/ → /oʊ/ → /oʊ/ + /-ən/
Pattern: /i/ → /oʊ/ (or /eɪ/) → /oʊ/ + /-ən/
- reap—rope (or rap or rape)—ropen (or reapen)
- speak—spoke (or spake)—spoken (or speaken or specken) 
- steal—stole (or stale)—stolen
- weave—wove (or wave)—woven (or weaven or weven)
- bear—bore (or bare)—borne
- swear—swore (or sware)—sworn (or swaren)
- tear—tore (or tare)—torn
- shear—shore (or share)—shorn
- awake—awoke—awoken (or awaken)
- break—broke (or brake or breck)—broken (or breaken)
- wake—woke—woken (or waken)
- beget—begot (or begat)—begotten
- forget—forgot (or forgat)—forgotten
- get—got (or gat)—gotten
- tread—trod (or trad or trade or trode)—trodden (or treden or troden) 
- come—come  (or came or com)—cummen Pattern: /ʌ/ → /oʊ/ → /ʌ/ + /-ən/
Pattern: /ɪ/ → /eɪ/ (or /æ/) → /ɪ/ + /-ən/
- bid—bade (or bad)—bidden (or beden)
- forbid—forbade (or forbad)—forbidden
- sit—sate (or sat)—sitten (or setten)
- queathe—quoth—queathen 
- scrape (screpe in Middle English)—scrape—screppen (or scrapen or screepen)
- see—saw—seen (or sawn)
- wreak—wrake (or wrack or wroke)—wreaken (or wrecken or wroken)
- lie (down)—lay—lain (from Old English licgan—læg—legen)
Pattern: /eɪ/ → /ʊ/ or /oʊ/ → /eɪ/ + /-ən/
- ache—ooche or oche—achen
- bake—book or boke—baken
- cool (cale in Middle English)—cool or cole—calen
- drag—droog or droge (or drug)—dragen
- grave —groove or grove—graven
- heave (have in Middle English)—hoove or hove—haven
- must (mote in Middle English )—must or moot—maten
- lade—lood or lode—laden (or loden or loaden)
- laugh—lough—laughen 
- shake—shook or shoke—shaken
- shape—shoop or shope—shapen
- shave—shoove or shove—shaven
- step (stape in Middle English)—stoop or stope—stapen (or stopen)
- wade —wood or wode—waden
- fare—foor or fore—faren Pattern: /ɛ/ → /ʊ/ or /oʊ/ → /eɪ/ + /-ən/
- stand—stood (or stod)—standen Pattern: /æ/ → /ʊ/ → /æ/ + /-ən/
- wash—woshe (or wesh)—washen Pattern: /ɔ/ → /oʊ/ → /ɔ/ + /-ən/
- claw—clew—clawn (or clewn)
- draw—drew (or drow)—drawn
- flay—flew (or flow)—flain (or flewn)
- slay—slew (or slow)—slain (or slewn) Pattern: /eɪ/ → /u/ → /eɪn/
Pattern: /oʊ/ → /u/ → /oʊn/
- blow—blew—blown (or blawn)
- crow—crew—crown (or crawn) 
- hew (how in Old English)—hew—hewn
- know—knew—known (or knawn)
- mow—mew—mown (or mawn)
- sow—sew—sown (or sawn)
- blend (bland in Middle English)—blend—blanden
- fall—fell—fallen (or fellen)
- fold—feld—folden (or felden)
- gang—geng—gangen 
- hang—heng (or hung)—hangen (or hungen)
- hold—held—holden (or helden) 
- hote (or hat)—het (or hight)—hoten (or hatten) 
- leap—lep (or lope)—leapen (or lopen)
- let (late in Middle English)—let (or leet or lort)—laten (or letten)
- read—read—readen 
- shed (shad in Middle English)—shed—shaden (or sheden)
- sweep—swep—sweepen (or swapen)
- walk—welk—walken (or welken)
- wax—wex—waxen (or wexen) 
- weep—wep—weepen (or wopen)
- weigh—wegh—weighen (or weyen)
- well (i.e. to well up)—woll—wellen
- wheeze—whez—wheezen (or whozen)
- wield—weld—wielden (or welden)
- crowd (crude in Middle English)—cred (or crede)—croden
- are—were—been 
- can—could—(none) 
- go (ga in Middle English)—yode (or yede)—gone 
- hit—hit—hit (in Middle English this was hit—hat or hot—hutten or hitten)
- put—put—put (in Middle English this was pit—pat—putten or pitten)
- wit or wot (wat in Middle English)—wisse—witen
- dig—dug—dug (~class III)
- dive—dove—dived (~class I) 
- fling—flung—flung (~class III)
- hide—hid—hidden (~class I)
- prove—proved—proven (~class V)
- reeve—rove—rove (~class II)
- ring—rang—rung (~class III)
- saw—sawed—sawn (~class VII)
- sew—sewed—sewn (~class VII)
- shoe—shod—shodden (~class IV)
- show—showed—shown (~class VII)
- sneak—snuck—snuck (~class I) 
- spit—spat—spit (~class III)
- stave—stove—staved (~class VI)
- stick—stuck—stuck (~class III) 
- string—strang—strung (~class III)
- wear—wore—worn (~class IV)
 Some nouns appear to display the same property, e.g. mouse (singular) vs. mice (plural); louse (singular) vs. lice (plural); man (singular) vs. men (plural); woman (singular) vs. women (plural); goose (singular) vs. geese (plural); foot (singular) vs. feet (plural); tooth (singular) vs. teeth (plural); brother (singular) vs. brethren (plural); cow (singular) vs. kine (plural); &c. However, these are not cases of ablaut, but rather umlaut. Umlaut is also responsible for the vowel changes in words like long vs. length; strong vs. strenght; old vs. eldest; full vs. to fill; cat vs. kitten; corn vs. kernel; to fall vs. to fell; to set vs. to sit; food vs. feed; lore vs. learn; whole vs. hale vs. health; foul vs. filth; fox vs. vixen; bond vs. bind; tale vs. tell; gold vs. gilt; near vs. nigh vs. next; etc. Learn more at http://en.wikipedia.org/wiki/Germanic umlaut.
 Some believe that the original form of the weak verb came about by appending the ancient equivalent of the word did to the end of the word being modified.
 I've drawn from a lot of sources (which don't agree with each other), including the Online Etymology Dictionary, the online Oxford English Dictionary, Ednew English (which also modernizes its spelling and contains many other non-standard verbs in their strong forms), Wardale's An Old English Grammar, Wikipedia, and Wiktionary.
 There are a few cases of profanity that fall into these lists, but I've chosen not to list them. If you really want to know, I'm sure you can figure it out.
 See http://en.wikipedia.org/wiki/Anglo-Saxon linguistic purism.
 See http://en.wikipedia.org/wiki/Germanic strong verb.
 There is also an irregular weak form of cloven: cleft.
 This would be pronounced LOZE, not LUZE (mouse over for IPA).
 The past participle lorn still persists in modern English in the words forlorn and love-lorn.
 This would be pronounced SHOWVE, not SHUV (mouse over for IPA).
 In Old English this was onginnan, so it would've been expected to become ongin—ongan—ongun (or ongunnen).
 In the sense of "fierce, savage, cruel", not "dreary, gloomy".
 You'll also find metathetic forms: arn—earn—urnon.
 The verb tind meant "to ignite", "to set on fire", "to light a fire", "to kindle", &c. It now only survives as the noun tinder.
 This ablaut series takes it one step further to include the noun: song.
 The obsolete past participles of sing (sungen) and swing (swungen) were intentionally used in the Christmas carol "Ding, Dong Merrily on High" to make it seem archaic. See http://en.wikipedia.org/wiki/Ding Dong Merrily on High.
 Beget, get, mete, speak, tread, and weave were originally in class V but have since changed. Awake, swear, and wake were originally class VI but have since changed.
 In Old English this was sprecan, so it would've been expected to become spreak—sprake—sproken.
 The past participle trodden still persists in modern English in the word downtrodden.
 This would be pronounced KOME, not KUM (mouse over for IPA).
 Most of you are probably only familiar with this verb because it appears in The Raven by Edgar Allen Poe: "Quoth the Raven, 'Nevermore.'" The weak verb bequeath is derived from this term.
 In Middle English the verb grave meant "to dig" not just "to carve". It has been replaced by the verb engrave.
 The past tense of mote (must) became the present tense and now has no past tense.
 The word laugh was sometimes written and pronounced as lawe in Middle English, yielding lawe—lew—lawn.
 In Middle English the verb wade meant "to go" not just "to walk in water".
 This would be pronounced CRONE, not CRAOWN (mouse over for IPA).
 This verb (which means "to go") is mostly known from Robert Burns' poem "To a Mouse" ("The best-laid schemes o' mice an' men / Gang aft agley" which is often modernized as "The best-laid plans of mice and men / Often go awry"). See http://en.wikipedia.org/wiki/To a Mouse.
 The past participle holden has mostly been replaced by held, but it still persists in the form beholden, which is used to mean "under obligation to" (i.e. "I'm beholden to no man.").
 This verb is essentially obsolete, but the form hight still crops up now and then.
 The spelling is deceptive. The present tense read is pronounced REED, while the past tense is pronounced REHD.
 The word wax was originally class VI (Old English: weaxan—weox—weaxen) but has since become class VII.
 The modern English verb be is an amalgamation of three (and possibly four) verbs. The past tenses (was and were) derive from Old English wesan; the indicative/imperative tense and past participle (be and been) derive from Old English beon; and the present tenses (am, is, and are) derive from Old English sindon.
 The Old Germanic word, kunnan, which gave rise to the modern can also produced the now-archaic ken, which meant "to know".
 The current past tense of go (went) is the past tense of the weak verb wend, which means "to go".
 Dive was originally a class II strong verb (Old English: dufan—deaf—dofen), but has since become weak and is now becoming strong again, but in the manner of a class I strong verb.
 Some derive sneak from the Middle English snike—snoke—snicken, which would make it class I, but this is debated.
 See http://www.youtube.com/watch?v=q51ld-scMI8.
 The modern verb to stick is from the Old English weak verb stician. It is often confused with the Middle English strong verb steke (steke—stak—stoken), which is from the Old English strong verb stecan (stecan—stæc—stecen).
Drawing of Medieval Jousters was photographed by IslesPunkFan (Neil R), available at http://www.flickr.com/photos/28110584@N04/3326739617.