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!

LetsPayTheBill.com - Free online tool to calculate the distribution of expenses during a group activity.

Tricount - Manage and share expenses with friends

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

SplittyPie - Create event, add users and their expenses.

ihatemoney - Manage your shared expenses, easily