W00T found a site that has most consle Emulators.
The Emulator Zone - Your Source for Emulation!
But, I'm not advertising, I'm here to give you some info about emulators
Q:
IS there an XboX 360 emulator
A: There is, BUT, you can not yet totally download games for it, and the games would be rather large in size, so, there is no perfect emulator, and don't expect one any time soon.
Emulators are not totally illegal, but, that doesn't mean that they are totally legal. The Emulator it's self IS legal, but, downloading ROM's It's self, (if you don't own the real game) is illegal.
Really, there are no emulators (that are perfect) for new gen consoles, I'll give you a list of consoles that have perfect emulators:
SNES
Nintendo 64
Atari
Nintendo DS
GBA
Gamecube (Depends on what emulator you get)
Thanks for reading this.