PSP Emulation is all I have been doing lately!
A quick rundown:
Turbografx 16 - PERFECT!
NES - PERFECT!
Gameboy - PERFECT!
SMS and Game Gear - Near perfect, full speed, sound is kind of raspy
SNES - at 333mhz and a FS of 2, darn near perfect on most games
Genesis - Full speed, but very preliminary sound
Neogeo CD - Full speed, no sound...some games are very glitchy
Neogeo Pocket - Slow as hell, no sound.
So far, this is what I have tried. As stated, the emulators I said were perfect are ones that I have no encountered a rom that would not load, no slowdown, full complete sound. The TG16 emulator is currently my favorite, because I loved that system and the emulation is so darn good...my PSP might as well be a Turbo Express with a better screen. I played Military Madness tonight for 2 hours. Needless to say, I am VERY pleased with the PSP's emulation. Easily the best handheld emulation I have ever experienced...with the Zodiac now 2nd on that list.
Also, I forgot to add, these are not limited to v1.0 Japanese PSP's anymore. This has probably been posted before here somewhere, but there is a swap method if you have two memory sticks and a v1.50 system software USA PSP....which I'm sure most do unless you updated. If you did, sorry, won't work unfortunately.