Find it
HERE I have not used this but it looks interesting, and its free
Meet Syntrax, the long awaited sequel to Jaytrax, the first software synthesizer and sequencer on the PocketPC. It has all the modern musician wants when away from the studio! A sequencer, sound synthesis and sample editor all wrapped up in a nice little package!
Syntrax runs on Symbian devices as well as the PocketPC. Syntrax is the first and only professional music package for the mobile phone.
Syntrax is packed with all the professional features you might expect from a mobile music studio. This includes MIDI support, a sequencer, sample editing, software synthesizer, realtime echoes, morphing etc.
Never again will you be bored in the train, never again will you whistle that tune and be not able to write it down. Mobile composing is here!