This has got to be the coolest multiplayer mod ever. The idea is that you float around with an hot-air balloon with a crew of four. One guy steers, one is on a look-out and the remaining two handle the cannons. You fight with other balloons and a lot of teamwork is required to win.
You need Unreal Tournament 2004 to play this mod.
Get it here or at least watch the trailer
http://ludocraft.oulu.fi/airbuccanee...hp?pg=download