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!
Evenfy - A free tool to manage household IOUs with roommates, split bills and track group expenses so that everyone gets paid back. On the web, iPhone, and Android.
Kittysplit - The easiest way of sharing costs with a group of friends
Splid - Splid helps friends manage their money.
Tricount - Manage and share expenses with friends
ihatemoney - Manage your shared expenses, easily