RIAA Radar

If you want to support musicians by buying their music, do a search on RIAA Radar first to make sure you're not also supporting the RIAA by buying CDs distributed under their labels. The RIAA are the ones who sue downloaders, and CDs released on RIAA labels are more likely to implement copy protection schemes. (see the2005 Sony CD copy protection controversy article on wikipedia).

If the CD you want is on a RIAA label, consider buying it used.
Also check out Boycott-RIAA.com.

Screenshot of RIAA radar in action:

Music-Map--Another way to discover new music

Type a band you already know into Music-Map, and it will generate a map of other bands/artists centered around the one you just entered--according to the site: "The closer two artists are, the greater the probability people will like both artists."
I'm finding the map's gentle quivering to be oddly mesmerizing.