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!
/Tab - The simple way to split a bill among friends.
Diggsweep - Easily create your own 'garage sale' to share with others
EquiTable - Split the bill fairly
PayPal.Me - Request money using your own personalized URL.
Spend Together - Spend more time on things that matter, rather that arguing about who owes whom and how much