iPhone Music Composition apps.
Sharing for other iPhone/iPod users looking for music app advice, and for fellow music theorists who may like me have been unuaware of what's becoming reality thanks to the unique power and interface. is one of the most amazing pieces of synthesizer workstation software ever created, and costs under $20. It provides features comparable to hardware and PC software many times the price (such as Kaos/303) and the manual printed from PDF is almost 50 pages!
After weeks of use I can report it is stunning, yet as understated as the iPhone itself is. It is NOT a sequencer solution, though there is some such functionality, but more an extraordinary instrument with strong live use potential. Some functions such as setting up programmable hot keys ("zones") specifically target live use. As an instrument, it offers an UNPRECEDENTED number of control axes (vert/hor/multi/tilt/roll/turn).
The synthesizer engine is extremely advanced (though essentially monophonic), providing benefits of additive and subtractive approaches. It includes comprehensive LFO/SEQ/Noise/SH sources, waves and filters, and comprehensive post-processing such as chorus, echo, eq, etc. The features are so advanced, that for example technically, one can route sequence to pitch creating a melody patch. The setting of parameters and assigning controls is brilliantly easy and uniform once the interface is familiar. Finally, the software includes a comprehensive patch management system, popup musical keyboard, innovative menu system, and a fundamental incorporation of multi-touch.
Bottom line, is a phenomonal iPod/iPhone program, which I will definitely be putting to routine use as a lead instrument. I've been studying electronic music for decades, and this actually achieves some of the highest academic concepts especially in the realm of non-musical controlled audio. BUT - Reading the whole manual is required! This calibre of capability cannot be simplified to documentationless, though you can get a long way in free play mode and flipping through presets.

SynthPond is a real implementation of the fantastic effectors and reactors visual model for music synthesis, as first seen in early multi-touch technology prototype demos. Place objects in 2D space, which emit and react to pulses of other objects with tones or sequences. Though it apparently lacks the additional manual parameter control seen in demos by turning an object, it does have the incredible capability of putting objects in orbits around each other. Not particularly useful in performance outside ambient genre, its certainly a fascinating passtime.

Pianist ("By Moo-Cow Music") is an actual full fledged piano simulation, as close as can technically be done given screen size. Effectively polyphonic, with well thought out controls for scrolling through the full 88, as well as soft and sustain pedals. Sounds are actual stereo sampled piano. Incredibly it even features volume expression by how keys are struck. AND a full featured easy to use real-time recording system, with overdub, editing, and multiple song storage! Finally, it has absolutely perfect integrated help, thougfh it doesn't need it. Unbelievable. Perfect for any piano capable musician for jotting quick musical notes, testing melodies, or for real performance or casual use.

Bloom is a "generative music application" by Brian Eno and Peter Chilvers (yes that Brian Eno). Bloom is art at a level I've only seen before in contemporary museums, and in Eno's great ambient spaces such as the Chicago United Airlines terminal. It literally creates ambient soundscapes interactively with no learning curve. The user's touchs are quantified into scale and tempo, woven over background drones, and eventually looped on long repeat and decay cycles. The interface is beautifully sublime and infant simple. Advanced users may select moods and some time aspects, or just run auto-compose. Finally, it even features recording/playback capabilities.

BeatMaker self described as the Mobile Music Creation Studio is by far the heavyweight app. It does not perform audio synthesis (as does), instead relying fundamentally on samples. It has most everything the typical mobile music composition tool user (aka modern musician) would seek in expensive dedicated hand-held units. Competitive even with major PC apps, though scaled back by interface and CPU limits. In BeatMaker one can control down to event patterns within notes within sequences within songs, but the editors are unique at each level. I have literally spent hours reading the manual and am still somewhat lost. Recording aside, it has aspects optimized for live performance, and once can play endless trance tunes basically out of the box using included demo sample kits. Fantastically, this program actually includes export to WAV and MIDI functions and integrated web server for remote access and file exhange. The value of dominating this tool is high, hopefully meriting the mastery curve.

BeatBox (BtBx) is a clean and simple 16 beat multi-pad sequencer, obvious enough for kids, super fun for adults. Great especially as a quick drum machine. Includes multiple tunable instruments, and reverse/distrortion/humanize features.

Drummer provides a good virtual set of basic percussion instruments, including multi-touch where applicable. For example, a working visual full drum set. Also congas, bongos, slide whistle, gong, cowbell, etc. Vendor also produces other theme specific sound effect suite apps.

Finally A Thumb Piano is an authentic recreation of the ancient tribal instrument.