Like many of my posts in the software and website categories, this one comes only after
Pandora has already gotten a fair bit of media attention. Nonetheless, I suspect it's a site many people still haven't heard about, but would enjoy.
Pandora is a web-radio site, but what makes it unique is that you can create a large number of personalized "radio stations," starting with just one song or artist you already know you like. From there, it's possible to suggest other songs to clarify the musical direction you want your station to go, or you can simply rate the songs Pandora suggests with a simple thumbs-up or thumbs-down.
For example, I started my first station out by suggesting Dave Matthews Band's
The Stone and, after a bit of fine-tuning, I've come up with
this station. I'm also experimenting with a couple of other stations to try to establish different stations for different moods, but all with music I like.
I haven't really done it justice with my description here - just give Pandora a try
here and see how you like it - it's a good way to get a radio station you like, and a good way to discover new music.