http://apps.facebook.com/saboteur_online/
You can invite your friends via facebook to play the game.
When you create a new game, you have 2 options: the standard game or the greedy gnome game. The last one is a variant in which one gnome is playing alone against all others. He wants to place the last card to establish the link to the gold.
Finally, you are free to chose how many rounds are played.