I never got into Second Life, but a coworker proposed crazy idea - Second Life is basically an editor! At the time we had to support Radiant for our games (I still do, a bit pain in the ass). But anyway - as crazy as it might sound, there are already tools/engines that would allow more than one people editing the world. Now with Second Life's ingame "editor" you wont be able to make an FPS, but it's not that far away.
So I installed just for the fun of it, played 15 minutes or so. But multi-player games never appealed to me (one exception is Heroes of Might and Magic hot-seat - it's real social multiplayer as people do take turns - especially fun when this goes for more than 24 hours, and everyone is pretty much drunk, smelly, some very tired, some can't stop laughing)
One idea I had is to create sort of a shared 'virtual-emacs' style 3d world where creating and doing new things was to write/execute functions (yes that's remote code execution).
I didn't feel up to putting enough time for something that probably only hardcore nerds would like though, so I didn't pursue it.
So I installed just for the fun of it, played 15 minutes or so. But multi-player games never appealed to me (one exception is Heroes of Might and Magic hot-seat - it's real social multiplayer as people do take turns - especially fun when this goes for more than 24 hours, and everyone is pretty much drunk, smelly, some very tired, some can't stop laughing)