The Bow-Legger: A person who runs like they just got off their horse.
The Bow-Elbow: Someone who runs with their elbows poked out and swing their arms, looking like they are trying to jab the people on either side of them…or break out into a do-si-do. Usually seen in combination with the Bow-Legger.
The Pidgeon-Toe: They run with their toes turned inward and appear to be trying to butt-kick the people on either side of them; it may include one or both feet.
The Tiny Stepper: They jog with such small steps that I could walk faster than them. It looks like they're barely even moving. They usually have an exhausted look on their face.
The Tiny Arms: Someone who runs with their hands tucked in close to their armpits, and sway their shoulders forward and back rather than moving their arms. Usually seen in conjunction with the Tiny Stepper.
The Turtle: A person who runs with their neck stretched forward…resembling a turtle. Usually seen in combination with the Tiny Arms.
The Arm Pumper: A person who swings their arms so violently that it looks like they're punching.
The Head Shaker: There is one man in particular who, when he runs, shakes his head from side to side, like he is emphatically telling a little child, "No, no." 
The Gazelle: A person who you can tell ran in high school because they move so gracefully and fluidly that they fly by you like a ship on smooth water.
The Wrist Flapper: They run with such floppy wrists that their hands flap all over the place. You wonder how they're not hurting themselves. It's most unbecoming when witnessed on a male. Often seen in conjunction with the Arm Pumper.
 This should not be confused with a Head Pumper, like Gus from Psych.
Statue of a man being tripped by another man from a sewer hole is by Bianca Bueno, available at http://commons.wikimedia.org/wiki/File:Statue tripping.jpg.