GovTrack.us  is a site to add to your reference website list and share with your users. It's been around for three years but as more and more features are added it's become a must for folks tracking what's happening at the federal level in government. The most useful feature to know about is the ability to monitor  bills, committees, and members via customized email alerts and/or RSS feeds. You can track specific bills or those on a particular topic. In addition, they've developed a widget  to add to your browser (Firefox 2.0 or Internet Explorer 7) that lets you search bills right from the browser. Found via LLRX.com .