Andy Baio likes to keep up with U.S. election news at the Memeorandum news aggregator, but wanted an easy way to see if the links on the page pointed to a liberal or conservative political site—so he put together a Greasemonkey user script that does just that. Baio's Memeorandum Colors script colors sites that usually link to conservative topics red, and sites that generally link to liberal topics blue (the colors get darker or lighter depending on the sites' linking activity). The result is a quick visualization of what kind of political site a link points to using colors. Baio explains:
The colors don't necessarily represent each blogger's personal views or biases. It's a reflection of their linking activity. The algorithm looks at the stories that bloggers linked to before, relative to all other bloggers, and groups them accordingly. People that link to things that only conservatives find interesting will be classified as bright red, even if they are personally moderate or liberal, and vice-versa.
Baio also explains how he put together the data and uses it with this script, which is a pretty interesting read for Greasemonkey developers. The Memeorandum Colors script is a free download, and it's available as a Greasemonkey user script, full-on Firefox extension, or bookmarklet that works with all browsers.