One of the best free music app that you can use for tablet is the PowerAMP, which is an Android app. The app offers you an engaging, visual-centric way to browse your music. You can as well get the SoundHound, Hitlantis and TuneWiki.
I don't know if you mean tab or tablet there's a difference but if you want tab then Ultimateguitar.com is good for drums guitar bass and some piano. if you mean tablet then I-tunes or something like that.