I commute in Portland ME, year round 18-30 miles roundtrip depending on the season...
In the winter I ride:
Schwinn Woodlands frame
48t track crank
16t ss cog
Deda Double Bolted stem
Action Riser bars
Deore XT brake levers
Tektro V-brakes
Nokian Mount n Ground Tires

This baby hasnt let me miss but a day of commuting this year...with record snowfalls, temperatures reaching -15 degrees and ice storms very frequent...it took the bike to its limit !
[img=http://img26.imageshack.us/img26/4719/1003222.jpg]



As for my non-winter commuter...

Spaulding Blade Frame
Brooks B66 double rail saddle
Soma Urban Pursuit Bars and Reverse Brake Levers
Dia Compe Side Pull Calipers
Sakae 175m Crank
52t Chainring
15t fixed cog
IRO Hubs
Deep V rims
MkS touring pedals

I recently made the switch back to my "fast" bike this week after being on my winter commuter since December 1st...What a difference !