well just have a thought, with it possilbe to create media player for the psp; cant someone create a media player that loads off a external source throught the psp's usb. So say you could connect a 2.5" hd to the psp's usb and play media files off it through the homebrew media app. Just an idea, is this possible.
of course you'd need to add a small battery pack to run throught the hdd's molex, (a 9v batt limited to 5volt would do the trick). the only prob would be using the psp as a usb host, but this is software side isnt it so cant someone do this.