GBEMU allows some PSP owners (Japanese modes with 1.0 firmware) to execute a Game Boy emulator on a memory stick.
From PSP411, "The first emulator for the PSP seems to have arrived. A crafty Japanese programmer has developed GBEMU for the PSP. At the moment, only PSP's with version 1.0 ROM will work. There are rumours and efforts going about to allow people to downgrade their ROM to 1.0, though nothing firm has been released as yet."
