I agree with buzzbee. I focus on keeping my feet not dry, but warm: full-coverage fenders, platform pedals, cheap plastic gardening/Croc-style clogs, and wool hiking socks with silk liners. With this setup, my feet are the last thing I'm liable to complain about on a rain-sodden commute. The clogs -- obviously unaffected by the water -- perform surprisingly well. The socks are just about dry by the time I set out for the return trip.