Several artists, including Coldplay (download leftrightleftrightleft here), have figured out that giving music away is a good thing for them and their fans. NIN released its 2008 album The Slip under a Creative Commons license (see FAQ for more info) and made it freely downloadable (here) in several formats including MP3, M4a, and several "better than CD quality" formats. For anything other than MP3 you will need to use a BitTorrent client such as the original client or many people’s favorite, uTorrent, or choose from this list comparing clients.
See also: This looks like a well thought out abstract by Michael Pfahl on Giving Music Away to Make Money. I have only skimmed it so I’m not entirely sure what points are made.