I remember Pitboss for Civ 4. It enabled multiplayer at a slower pace, much like hotseat, only over the internet.
Civ 5, as of yet, does not have Pitboss, but some innovative people may have found something just as good.
As BigSmooth posted on the Civ5 thread, Giant Multiplayer Robot, located
here, enabled hotseat games to be played more effectively over the internet. Games can be timed, so if a player doesn't take their turn in 24 hours, the AI takes their turn for them so the next player can go. It effectively replaces PitBoss.
The site was verified by the folks over at CivFanatics as legit, and you have to have a Steam account to participate (which you have to have anyway to play Civ 5).
You can download the app, or just check the website (I think you're notified by email as well, when your turn is up).
I gauging interest in a Gods and Kings game, maybe 5-7 players. Play a turn once every 24 hours. Nice, slow pace.
Anyone interested? I can have a game set up in a jiffy!