RetroArch

[nickblame]

RetroArch is a frontend for emulators, game engines and media players.

It enables you to run classic games on a wide range of computers and consoles through its slick graphical interface. Settings are also unified so configuration is done once and for all.
This is more or less the swiss army knife of emulators.
Each emulator is incorporated in retroarch as a "core" and the impressive thing about this structure is that it works very well and it was widely adopted by many different emulators.

RetroArch Official site