I just discovered a project called Mamehub. It basically works like Kaillera except it's p2p (not server) based, and unlike Mame32k 0.64 with Kaillera, Mamehub actually stays up to date with the latest version of Mame! What really stands out to me about this project is that, unlike Kaillera, Mkak, and OGmk2, the project is still active and being updated.
There also seems to be 4 players for UMK3! :O
https://www.google.com/search?q=ultimate+mortal+kombat+3+mamehub&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb
https://www.facebook.com/MAMEhub?fref=nf <Like their Facebook page.
There also seems to be 4 players for UMK3! :O
https://www.google.com/search?q=ultimate+mortal+kombat+3+mamehub&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb
https://www.facebook.com/MAMEhub?fref=nf <Like their Facebook page.