Trek 520
I replaced the partial fenders with full fenders, and added a cycling computer and lights. The Axiom Rainrunner Trekk fenders are supposed to support up to a 700x45 tire, but the included stays are too short. With them extended to the maximum I barely have enough room for the 700x32 tires that came with the bike.

I've been using a Canondale Harvester for carrying clothes, and bike tools to school. I leave that bag in a locker with my cycling shoes, shorts, etc.

I use a Racktime City bag for books, ipod etc and keep it with me throughout the day.