MAME - Multiple Arcade Machine Emulator
With MAME you can play Arcade games on your computer. You need the ROM files (Read Only Memory) of the Arcade games. You can find them all over the Internet. MAME has many functions, for example you can take screenshots of the games while playing them, good for sprite ripping.
You must own or have license to each ROM set that you wish to use in MAME. The catch is this - most companies won't sell you ROMs or provide a means for you to purchase them. In fact, about the only way you can own them is by owning the original arcade boards. Worse still, even if you own the arcade boards, there is the problem of being able to dump the ROM images.
MAME for PC
Get the newest version of MAME for PC
Mame for MAC
A version of MAME for the Apple Macintosh. Plays most games like the PC version.