Where are contracts used in the real world
Gregory Maxwell, Pieter Wuille, and theymos are using a 2-of-3 address to store a bounty for contributions to CoinJoin.

https://bitcointalk.org/index.php?topic=279249.msg2983911#msg2983911 

Update: A 2-of-3 escrow and arbitration site recently launched: https://www.bitrated.com/