Sony[]
PlayStation / PS1[]
See PSP Eboots.
Nintendo[]
Game Boy Advance[]
TempGBA4PSP is the most recent GBA emulator for the PSP, and has superior compatibility with most problematic games (Golden Sun, for example).
GpSP[]
GpSP is an open-source Game Boy Advance emulator created by Exophase and is probably the best Gba emulator on the psp.
Game Boy / Color[]
MasterBoy 2.10 or RIN 1.32 or GeMP 3.3 Final
GeMP and RIN have some incompatibilities with later PSP models. GeMP is incompatible with GameCategories.
Famicom (NES) / Famicom Disc System []
NesterJ 1.13 beta2 or NesterJ AoEX
AoEX is based on NesterJ 1.12 Plus 0.61 RM, so it includes features like rewind mode, cheat codes support, rotated/mirrored screen, sepia palette, support to rare mappers (the pirate bootleg FF7 works on it), etc, but its compatibility is inferior to 1.13 beta2.
Super Famicom (SNES)[]
SNES emulation isn't very good to begin with, but this is the fastest and most compatible emulator available right now.
Nintendo 64[]
Most games are unplayable, but there's a small amount of them that work really well with the right settings (Quest 64, for example).
Nintendo DS[]
Probably the only ds emulator and is very experimental and support for it stopped a long time ago,and you can't a touch or second screen on psp properly (unless you flip the psp sideways), so it was a failure from the start.
SEGA[]
Genesis / Sega CD []
Master System / Game Gear []
MasterBoy 2.10 (also compatible with GB and GBC)
Other Consoles[]
PC Engine / CD []
Neo-Geo Pocket / Color[]
WonderSwan / Color []
Oswan (multi-emulator)
Arcade[]
UOcps1psp (CPS1), UOcps2psp (CPS2), UOmvspsp (Neo-Geo), UOncdzpsp (Neo-Geo CD)
Other Consoles (retro)[]
Atari 130 / 800 / 5200[]
PSPAtari or Atari800 (800 only)
Atari 2600[]
Atari 7800[]
Atari Lynx[]
Colecovision[]
Intellivision[]
Vectrex[]
Computers[]
Amiga 500[]
Amstrad CPC[]
Apple II[]
Atari ST[]
BBC Micro[]
Commodore 64[]
Commodore Plus / 4[]
McOS 0.x[]
MS-DOS (SCUMM)[]
MSX / MSX2 / MSX2+ / MSX Turbo-R[]
Sinclair ZX81[]
Sinclair ZX Spectrum[]
Sam Coupé[]
Thomson MO5[]
Thomson TO7[]
TI-99[]
TRS 80 / Tandy Color Computer[]
MISC[]