Tribeez - Flatshares, families, friends...
/Tab - The simple way to split a bill among friends.
ihatemoney - Manage your shared expenses, easily
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!
Raft Calendar - A fun and beautiful calendar for couples and close friends
Splittable - Shared living made simple