Sound-activated rumble mod
F00 f00 over at Acidmods has come up with yet another PSP modification, this time implementing sound-activated rumble. His previous attempts at getting this to work weren't quite as successful, as he was unable to get the vibrating motor to turn off once it had been activated. F00 f00 explains how he accomplished this modification on the AcidMods forums and you can check out the demo video he made via the link below.
Watch Sound-activated rumble mod by F00 f00Via
AcidMods