I'm surprised I haven't seen more about OpenCongress in the sites I read. It is one of the better Congressional resource sites I've seen. I can't wait for the next release which will include the ability to tag bills, and follow the Congressional calendar.

It nicely bridges the gap between official government items (votes, bills, hearings) and public discourse about those items. Most sites like this play one side or the other.

They've got a Trac site for developers. Unsurprisingly it's written in Ruby on Rails.