Spring and plug-in to allow my PS One to play CD-R(dating myself, I know) game copies and PAL imports. As well as ability for cheat codes, etc.
Modded XBox using Nightfire soft mod to run the Phoenix Launcher Linux OS; added NES, SNES, N64 Emulators and a bunch of roms. Also able to play DVD burned copies of games and PAL stuff. Added decals and changed light for a blue look instead of green.
**Disclaimer: I owned all games and roms that were copied, for backup purposes only of course**
Haven't done anything with my 360 yet, other than custom background on Live screen and using a large capacity USB thumb stick to watch movies from my computer(burning to disc is so passé)