-PSX,CPS1, CPS2,GBA,SNES, Genesis, N64, Neogeo, Gameboy, Amiga, PC Engine, TurboGrafx,etc
Just for 100€ (Second hand PSP with CF + Memory Stick) you can emulate all this platforms in a 4.3" screen!
After having tested several emulators, the best one for me is Uo Gpsp Kai 3.3 Test 2 Build 13 released on 01/05/2009. (find it at dl.qj. net)
As long as you put the roms decompressed they will work. I've tried 115 diferente roms so far and all working great. And, unlike gpSP, you can play with...
I didn't know this game existed but since I love SRPGs I'm sure it's a must-have (And Atlus it's for me one of the best videogames companies ever, if not the best one)