As I'm sure everyone knows, the DS has GBA compatibility built-in which results in a wonderful back-catalogue of games (as well as some unbelievable dross, but show me a platform that hasn't got that...). Well, the PSP-only guys n' gals (hat-tip, Jimmy Saville) out there need not be jealous, as there is now a GBA emulator for the PSP, courtesy of a VBA port by the wonderfully named ZX-81.
I've not tried it (quel surprise...) as I own a DS already. I suspect it's not full-speed, seeing as it's written in C, but it's still quite an amusing prospect.
This emulator's been around for a while now, but I've never gotten around to posting about it (I know, bad Merg...).