Everyone, or someone, or no one infact, should at least get it and try it, it's called project64k or mupen64k either one but project64k is more popular but the newest one not many people use so you might need to find an older version like '1.1'
^ Mario kart 64 online
Also there is a Super Mario 64 Hack that allows 2 players, as well as an original hack with it's own levels featuring two players. All of the stuff is at the official Project64k site which you can find on google.
^TAS'd Sm64 Multiplayer (Which is used on the same computer but you can play it online too but only with project64k.)