FastChords HD App for iPad
'Quickly map chord symbols to piano keys with a unique calculator-like interface.
Excellent for learning new songs from so-called "real books" or from music scores. Or just for playing with your own chord progressions.
May be the only piano chords reference source you'll need. And definitely the most fun.
* familiar calculator-style interface
* ability to save and edit chord progressions
* customizable keys to match chord symbols
* vast library of over 300 chord symbols
* ability to construct slash chords
* easy chord inversions
* 5-octave keyboard display
* great sound.'
This app costs $2.99