BikesDirect.

Dawes SST.

Light, durable, got me around campus just fine. Comes with a good wheelset, Alex R450's, and has the bullhorns, which I prefer. Also comes SS/Fixed so you can choose, though I like riding fixed, just because of feel. I've beaten the living crap out of mine, riding it around, locking it up, and just general ride and it looks fine w/ all the scratches.

Other popular choices include the Mercier Kilo TT, Windsor Clockwork, Craigslist Conversion.