My winter commute bike:

Gary Fisher 229 with the following changes:
Surly Karate Monkey Forks
Schmidt SON dynamo hub
Schmidt E6 headlight (Cateye EL500 backup)
D Toplight Plus taillight
Tubus Cargo Rack
Nokian 106 700x45C Studded tires
beartrap pedals with Powergrips
SKS Fenders

My commute:
12 miles each way -- 8 miles on country roads and 4 miles in town. Mostly dark both ways.