Phillips CDi: CD-Ice Preview
Plays one game, only publicly available CDi emu at the moment.
DreamCast: Chankast Alpha 0.25
Excellent DC emu, though has a fair few bugs.
WonderSwan: Cygne 2.1a
Good little emu.
LaserDisc: Daphne v0.99.6
Great emulator, plays every laser disc game I have.
PlayStation One: ePSXe 1.6.0
Remains the most compatible and widely used PS1 emu around.
PlayStation Two: PCSX2 0.8.1
The only project being worked on atm for PS2 emulation, and getting much better.
Panasonic 3DO: FreeDo 1.7
Excellent 3DO emulator, and runs very fast with good compatibility (With cooked iso's only (2048)).
MegaDrive / 32X / SEGA CD: Gens 2.11
Legendary, and the damn best!!
Atari Lynx Handy 0.90
Best and only one I have ever used.
Turbo Graphics 16 / PCengine / PCE-CD: Magic Engine 1.0 PR8
Amazing PCE emu.
Arcade: MAME 0.xxxxxxxxxxx.xxxx.xxxx.u.blah
For a general arcade emulator not bad (it covers stuff that nothing else does), but if you're after playing NeoGeo / CPS / Model 2 etc...use nebula!!!
SNK NeoGeo CD: NeoCD 0.3.1
The only one I have ever used, rumour has it that the next Nebula version will support NeoGeo CD
NES: Nestopia 1.09
I have never found a more compatible emulator for NES.
Nintendo 64: Project64 1.6
Simply amazing, but still N64 emulation needs work!
Atari Jaguar: Project Tempest 0.95
Good emulator, and certainly one of the best for this system.
Nintendo GBx / GBA: Visual Boy Advance 1.7.2
The best, simple huh.
SNES: ZSNES w1.42
Amazing, though the GUI sux cock.
Nintendo GameCube: Dolphin
The only current and most compatible GC emu out there.
Sega Saturn / ST-v: Satourne
Lets ignore crapini shall we folks, this one is legal, legit, and amazingly good.
There are many more out there, I haven't even started with Computer stuff, like Atari ST, C64, BBC Micro etc......TOSEC.....errfffff