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!
iLend - Keep track of the things you lend and borrow.
/Tab - The simple way to split a bill among friends.
PayRequest - SImple Fast Payment Links
Dinngo - Splitting payments the fun and easy way
PayPal.Me - Request money using your own personalized URL.