Yeah, no kidding!
Protest Records are letting you to click links on their pages to mp3 sources (and download it, ofcourse!) for free. The mp3s belongs to various artists (just check it out). But before you start downloading, please keep this in mind : "use 'em for yrself. give 'em to friends. just don't sell 'em." (Protest Records)
Well, here's the address: http://www.protest-records.com/mp3/index.html
Hope it inspire you.