forScore, in simple terms, is a PDF viewer specifically for reading sheet music files. What makes it helpful for the music teacher or performer is the way the pages within a PDF can be rearranged and annotated. You can also add to your score library by simply taking a photograph of your hardcopy sheet music. Alongside this you have an inbuilt metronome, tuner and audio recorder to capture ideas. If you want to get really technical you can even add a foot-controlled page turner which is powered via Bluetooth.

All in all, this is a pretty sophisticated and useful app for anyone who sight-reads music often.

Download forScore here

This is an invaluable resource to me as I'm forever needing to print out various different pieces of blank music for my students- whether it be Guitar TAB, Bass or Ukulele TAB, Treble or Bass Clef Standard for Keyboards, Drum notation or simply a blank stave. All staves are customisable, you can add time or key signatures or change the size/amounts of staves and print. 

http://www.blanksheetmusic.net