PSPSeq is a powerful homebrew music creator for the Sony PSP.  It is capable of 16 simultaneous instruments of either built in synthesizer or .wav sample playback.  Synth instruments come in a variety of different synth+effect combos.  

The 64 step sequencer has unique synth and effect parameters for each step, and can combine patterns into songs of up to 100 unique patterns.

'[l[http://www.dspmusic.org/psp/[website]