Bandcamp just recently launched their Facebook App and I highly suggest anyone that is in a band (or anyone you know in a band) get their act together and implement it into their Fan Page. There are other alternatives out there that have similar functionality but I've always been a huge proponent of Bandcamp since it benefits the artists the most directly, monetarily especially. It may not have all the bells and whistles of some of the competition but I enjoy that your best bet for selling music can now also be directly tied into your Facebook page - fewer hoops to jump through is always a good thing.