There are other mafia variants such as "two rooms and a boom" style (
http://www.tuesdayknightgames.com/tworoomsandaboom/) where there is no elimination, and the goal for one team is to get their "bomber" in the same room as the "president" of the other team by the end of a certain day. At the end of the day each "room" votes for a negotiator who will pick to transfer a certain number of players from their room to the other room thus shifting the balance each day but also potentially moving the critical roles from or to their win conditions.
Then there are support roles to make the win conditions harder (team doctor must find out "president" before last day is over, team engineer must find out who the "bomber" is to make sure bomb is successful prior to end of last day), or third party roles with alternate wincons etc...
Pro's: no elimination so people stay in the game. Fixed length of game.
Con's: needs active players since if a person with an critical role doesn't show up then it's almost impossible (suppose a detective role could help mitigate this somewhat). Some roles can't be modified for forum use. host needs to control two rooms (threads) to prevent people from posting in the wrong one and hard to control PM's across rooms.