Digital music service WaTunes has created a music download application for Facebook that allows users to buy and download songs without having to leave the social network.

WaTunes originated as a digital distributor, placing artists songs for sale with such digital retailers as iTunes and others, but as of April 1 is no longer in that business. In February, it launched the WaTunes Markeplace, a music download service of its own that features music from major labels Universal Music Group and EMI Music, as well as several independent labels.

The Facebook app, called MusicStore, essentially integrates the WaTunes Marketplace into the social network. According to CEO Kevin Rivers, the company is brokering a deal with MediaNet to power the backend of the service, which would give it access to the entire MediaNet catalog.

The app also lets users post albums and song reviews to their Facebook “wall.” Unlike other Facebook music apps, MusicStore does not require users to leave Facebook to complete their purchases or create a WaTunes account. Users will have to enter their credit card and contact information when buying music, and then get an e-mail from the system with a link to download their purchased tracks. Rivers says the system does not store credit card information, so these details will have to be entered for each subsequent purchase.