Wow, thanks for the pointer to GovTrack. Thomas has the data but a terrible interface. GovTrack.us really puts all of a bill’s information together well!
I find it to be very capable, it can do email alerts on various trigger points (cloture votes, etc) but I admit I don’t take advantage of all that. I just like the interface, and the fact that you can get some opinion there as well. (with a grain of salt, of course)