We've featured more than one MP3 search engine before, but most are filled with ads and confusing layouts. Sad Steve is a plain but effective MP3 search engine and player, complete with profiles on new bands to get you started.
Since Sad Steve is not out to make any money, the site is completely devoid of ads and other intrusive features, separating it from the dime-a-dozen MP3 search engines out there nowadays. It's just a simple engine from which you can search, download and stream a ton of different songs (even fairly obscure stuff). The site also hosts profiles of new indie bands on the site, and you can pledge money to bands that you like and would like to see succeed. It also has a nice "Percolator", which randomly generates a 20-track playlist every 20 minutes, so you have something to listen to even if you don't know what you're in the mood for.
Sure, it isn't the best-looking site around, but its simplicity gives it an ease of use that other sites don't quite have, and the lack of ads all over the place is a really nice change of pace. It won't give you the powerful playlist-crafting abilities something like Grooveshark or Mixtape.me will, but if you're just looking for a few tracks (or for a few new bands to check out), it's a pretty good place to start. Hit the link to check it out.