Pandora

Highly Recommended is probably the last to know about this one, but it's new to us, so there it is. Pandora is a web-based application similar to MusicMatch: it helps you find new music with qualities similar to stuff you like. There are free (ad-supported) and subscription (not) versions, and direct links to Amazon if you want to buy the CD. It's a bit faster than shuffling through everyone's iMixes, and you get the full song, in a 128kbps stream.