Yahoo Pipes is a nifty service that [Steve Ivy->] tipped me off to. It provides a visual programming language, like Quartz Composer or Isadora, to suck in data from the web, process it, and spit it back out again. It makes it pretty easy to do interesting mashups, like a search for apartments in your city that are near parks, or building a news feed that consolidates article on a particular subject from lots of news sources, or finding and linking to videos for the top 10 songs on iTunes.

Fun stuff, but still not for the technically faint of heart.