LetsPayTheBill.com VS WhoseBill

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!

Kittysplit - The easiest way of sharing costs with a group of friends

Tricount - Manage and share expenses with friends

ihatemoney - Manage your shared expenses, easily

WieBetaaltWat - With WieBetaaltWat you can manage a list with your shared expenses.

SplittyPie - Create event, add users and their expenses.