A free app for Android, by Julian Casadesus.

Compose your own music with ease whenever and wherever you are with TuxGuitar. This open source multitrack tablature editor and player for Android features various functions that will help you in composing an original masterpiece.

It has a table editor where you can input the notes and cords you want, a score viewer to see the whole thing, and an auto-scroll function so you can play the piece without having to manually scroll it.

TuxGuitar also features various instruments such as piano, harp, and an acoustic guitar. You can even use it to lay over your voice and use various effects to boost the musicality of your piece!