From Cool Beans Software:
iKeySig is a musical key signature reference tool that displays all of the relevant information for each key including the key signature, the notes of the scale on a piano keyboard and each of the chords of the key for all of the possible keys. iKeySig is a simple no frills quick reference that will appeal to professional, student and hobbyist musicians.iKeySig is a great teaching and learning tool. It visually displays the notes and chords in such a way that the user can gain an understanding of how music works. Once you can relate the major minor chords of one key, you can use that same knowledge in any key. Check out our other iKey app: iKey Transpose.