Which facebook application you know have maximum monthly active users ? We may not have the right answer but whoever knows app having maximum number wins.
friends for sale/mafia wars/firmville? dunno, i don't use facebook, but htese three are the most discussed apps in our school :/
Here is the poll by Mashable as well to confirm. http://mashable.com/2009/11/07/top-10-facebook-apps/
