Simple Songwriter for iPhone

I've not tried this app but it does look interesting. Not sure exactly how it works, but it could be interesting. Here's the description:

Beginners to advanced musicians can use this app to leave thinking behind and bring the fun back into creating music. All the chords given sound great together and most pop/rock songs will use a combination of these chords. The touchscreen gives you the perfect environment to quickly and easily generate song ideas. When you have a great song idea, record it for later practice on your chosen instrument. List view allows you to browse your songs chords, while the song key section can transpose your idea to any key instantly

Use Simple Songwriter when you want to:

• Easily and quickly generate song ideas
• Record song ideas for later playback
• Find Chords that sound great together
• Help identify the key of a song
• Instantly change the key of a song
• Easily examine the chord progressions used by your favourite songs

What's new

• Emergency Bug fix for iPod Touch users!
• Completely revised User Interface
• High Quality Samples
• Completely revised sound playback (Nearly zero latency chord playback)
• 1/4 Beat quantizing
• Song Chord list now editable (timing & chord type / inversion)
• Metronome can now do 3/4 timing if desired
• Display chords as Sharps # or Flats b
• Much better audio track recording and playback