Splitwise - Splitwise is a free tool for friends and roommates to track bills and other shared expenses, so that everyone gets paid back. On the web, iPhone, and Android!
Splittable - Shared living made simple
EquiTable - Split the bill fairly
Roomr - Discover great people to live with
Dinngo - Splitting payments the fun and easy way
Spend Together - Spend more time on things that matter, rather that arguing about who owes whom and how much