amazon.com
In addition to selling (nearly) everything under the sun, Amazon.com has an eerily accurate recommendations service. Also a plus: the rookie reviews posted by Amazon.com shoppers.

barnesandnoble
Browse music by style at the Listening Wall and get a taste before you buy.

borders
Borders' NetCafe features live chats and interviews, a nice bonus considering you have to make the latte yourself when you shop online.

cdnow
CDNow is the brand name for online music buying. The Cosmic Credit program gives buyers points for purchases that can be redeemed for store credit or merchandise.

insound
Looking for an alternative to mainstream online music stores? Insound promotes indie music as well as your neighborhood record store -- with ten times the selection.

spun.com
Where else in the world can you buy CDs online -- and pay with CDs? It is hard to believe no one thought of this idea earlier. This is by far the best way to unload used CDs -- even those the snotty used records stores don't want. Also, Spun's depth of used CDs runs very deep.

tower records
This music megasite offers great depth, plus Pulse magazine and Trivia Challenge, a diverting music trivia game.