For policy geeks only,

... rabid partisans with blinders move on.

If you armchair quarterback policy, not just politics, GovTrack.com will be your own little button-down porn. You can monitor what your representatives are introducing, how they're voting, and what they're saying on the floor. If you don't know who they are, it's easy to find out. You can even monitor legislative actions by issue, and get your monitor info by email, etc. One suggested improvement: the ability to summarize at least the most popular bills so users don't have to wade through lawyerspeak. Thankfully, Citizen Joe helps, and is linked to from GovTrack issue by issue.

If you're both a technical AND policy geek, here's how GovTrack's creator, Joshua Tauberer explains what it does:

The more knowledge citizens have about government the better. So how can we use XML and the Semantic Web to make it easier to get that knowledge, and to foster civic participation? This is a question I've spent a lot of time on over the last few years while putting together www.GovTrack.us, a site that gathers existing information on the web about the U.S. Congress and puts it all together in new ways, using RSS feeds and Google Maps, for instance. The site is possible because the government has been posting the relevant information online for a while, but in scattered locations. For instance, legislation is posted in one place and votes on the very same legislation in another. Gathering the information in one place and in a common format gives rise to new ways of mixing the information together. Each day GovTrack screen-scrapes these sites to gather the new information. The information gets normalized and goes into XML files so that when GovTrack wants to display the status of a bill to a user, it can just run an XSLT stylesheet on the XML bill file.

article for the above quote