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!
Tricount - Manage and share expenses with friends
ihatemoney - Manage your shared expenses, easily
Settle Up - SETTLE UP is an indispensable app for friends and flatmates who need to keep track of shared bills...
Sesterce - Sesterce makes it easy to split bills for a group of friends, a couple or roommates. Add all the expenses and Sesterce settles it up!
MoneyBuster - Multi-project shared budget manager able to sync with self hosted FOSS services