Amazing Piano is a music app for iPhone and iPod touch that allows the user to “play piano” via an onscreen QWERTY keyboard. It features both free and practice modes, the latter for playing melodies by pressing keys as the letters for them scroll across the screen.

Pianofly by Pro Synth is a programmable FM synthesizer app featuring a one-octave onscreen piano-style keyboard. It uses a novel approach for accessing notes outside of this range; the player simply flings the keys to the right or left.

Chordica is a fun and easy to use music app. It’s innovative design lets you memorize songs using numbers instead of notes, which allows you to play a song in any key using the exact same screen taps. The app has a good sounding piano sample and enough adjustments to allow flexibility without being overwhelming.