Track or SingleSpeed Cranksets

zane chaos from http://sheldonbrown.com/harris/cranks/130-single.html :

We generally recommend 165 mm length cranks for road fixed-gear use. This shorter length makes it easier to spin faster cadences, and also reduces the risk of striking a pedal while cornering (with a fixed gear, where you have to pedal through the corners, this can be an issue.)

there is also more info on sheldon's site here