I have to recommend these guys, not because they've asked me to - Hell, they wouldn't need to. I've made three orders (a couple of two CD orders, then five at once - But more on that in a moment) and received two free CDs from them already.
Anyway, check out
CD Baby. They predominantly stock lesser known American artists, but the range they stock is phenomenal! You can browse by mood, artist and style plus they have decent recommendations and usually a lot of in depth info on each album, downloads etc. Have a looksee, but they have everything from 80's hair metal to drum'n'bass, avant garde improv to solo acoustic.
But the best thing, for those that like to take chances, is that they have a $5 dollar sale on. Buy three or more titles from their sale and you get them for $5 each. I ordered 5, got them delivered with a free album for under 20 quid.
I can't recommend this site enough for anyone that likes taking a chance on music. Plus they take Paypal, which has made it far too easy to buy foo.