An arcade emulator, just add games apparently.

[Iowatech]

If anyone wants this, it is now open source:
MAME Multiple Arcade Machine Emulator
Just for grins I downloaded it. There doesn't appear to be any games included.

[garycimera]

MAME has never included roms. They must be acquired separately. I've been a MAME user for 16 years now. Built my own arcade cabinet also.

[Kidaver]

The Emulator Zone - Your Source for Emulation! has tons of great emulators....ROMS on the other hand they don't...there are ways to acquire them...this kept me from being bored when I was in Iraq with downtime...I've got probably 2k+ roms of all the old games I grew up playing...