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!
BillMonk - Billmonk lets you keep track of debts between friends.
Kittysplit - The easiest way of sharing costs with a group of friends
PocketGuard - PocketGuard categorizes and organizes your expenses, monthly bills and subscriptions into clear, beautiful tabs and graphs, so you will always be on top of your finances.
ihatemoney - Manage your shared expenses, easily
Goodbudget - A home budget app based on the envelope budget system. Available on the web, Android, and iPhone.