Rhapsody is an excellent subscription-based music playing service available on all Android devices.
The app gives you access to millions of songs in just about every genre imaginable. You can listen to band-based radio stations, similarly to apps like Pandora, or you can actually save and download specific playlists. You can search by artist, album, genre, or whatever, and view things like top tracks and similar artists.
The app also provides access to biographies of specific artists, and sometimes Rhapsody specific interviews. This is a solid app, and a great alternative to buying songs that you might grow tired of in a year. Of course, you can also purchase songs permanently if you want. My only complaint is that the layout could use some work.
Rhapsody turns your Android tablet into a comprehensive music library.