5. Mob Wars

Daily Active Users: 493,531
If you’ve ever wanted to be a somebody in, say, the Mafia, “Mob Wars” is your chance. This virtual gangster game starts players in the lowest ranks of the criminal underworld - mugging folks and stealing cars. As you gain notoriety and cash, players can start challenging or completing hits on other mob bosses to rise to the top.
4. Friends For Sale!

Daily Active Users: 549,692
Who’s your most valuable friend? This application lets you “buy” and “sell” your friends like pets, then creates a leader board ranking them accordingly. Prices rise with each transaction. You can also force your pets to show off, say by poking someone else or sending gifts to other pets. You can give them nasty nicknames or virtual gifts.
3. Texas Hold’Em Poker

Daily Active Users: 660,854
Where isn’t Texas Hold’Em popular? That’s really the question. Cards, of course, are all about social competition, either on a screen or on a felt-covered table. Just like in the real world, Texas Hold’Em is winning more fans than other poker games, hands down.
2. Owned!

Daily Active Users: 678,982
This is a game of net worth. Buy and sell the photos of friends and strangers, a popular activity on Facebook, on the open Owned! market. As you purchase folks (or give the gift of “owned friends” to other people), you earn game currency that can be invested in even more valuable friends.
1. (Lil) Green Patch

Daily Active Users: 735,473
This garden-tending game preys on users’ eco-consciousness by promising it will save one acre of rain forest for every 10 digital plants sent to (and accepted) by Facebook friends. As a bonus, users get a Tamagotchi-like horticultural experience of tending a garden by buying rare plants and other decorations to expand their virtual green patches.