I haven't mucked around with MAME (multiple arcade game emulator) for years so I decided to snoop around and see they're up to. Oh boy, have I been missing out. This is the *COOLEST* thing I have seen in a long time! Kaillera was created by a Nullsoft developer, who you should know are responsible for Winamp. From the Kaillera website,
"Kaillera enables emulators to play on the Internet.
It consists of a client and a server. The client is usually embedded into your favorite emulator and the server is a stand-alone application that needs to be run on a machine directly wired to the Internet."
There is a SDK for Kaillera so any developer can incorporate it into their own emulator, so potentially, ANY emulator out there can be made so that you can play the games over the internet (and Lan too) with up to 6 players, if the game supports it! Currently, there are Intellivision, Atari 2600, Neo Geo, NES, Nintendo 64, Sega Master System, Sega Megadrive and Amiga emulators, along with MAME (and we're talking hundreds of arcade games here) using Kaillera. I'm looking at the Kaillera site, and there are people playing the arcade Street Fighter Alpha 3 game online now. Awesome. :)