Just came across this toy, download a free demo, gives ya something to do on the plane:
http://www.klaar.com/
Syntrax for PocketPC
Upto 8 stereo audio channels simultaneously (previously only 6)
Playback of samples with bi-directional looping support
Realtime sound synthesis with 15 sound generation effects
Realtime effects like filters, morphs and echoes
A built in small sample editor
A full featured sequencer
Dynamic playback options (songspeed, groove, muting etc..)
Realtime instrument parameter changing
A ******** of preset songs and sounds for you to start working with
User adjustable sound quality for slower PocketPC's
New Features:
Memory card support
An improved graphical user interface (knobs and dials)
An enormous speed gain. The sound engine and GUI have been hugely improved in speed.
Loads of small improvements users have emailed
A new name: "Syntrax" (instead of Jaytrax)