A hobby of mine is creating music on Apple products, Logic, Ableton Live & Garageband on the Mac and now leveraging the many Touch OS applications on my iPhone & iPod Touch.
Touching briefly on a few of the better applications available:
- Beatmaker - think of this as a loop/beat version of Garageband.
- Noise.io - a full featured soft synth that has a link with Beatmaker, allowing you to use content you created in Noise as loops in Beatmaker.
- BassLine, iSyn & Technobox are all variations of a synth & sequencer. iSyn is a lot of fun.
- iDrum, MegaSynth, Jasuto, NlogSynth are all virtual instruments.
If you are musically inclined, or just like to noodle around there are alot of great options.
A good blog to add to your RSS feed if you are interested in music creation applications for the iPhone/Touch is: Palm Sounds.