Grisbi - Accounting for everyone !
Kittysplit - The easiest way of sharing costs with a group of friends
Ledger-cli.org - Ledger is a powerful, double-entry accounting system that is accessed from the UNIX command-line.
SplittyPie - Create event, add users and their expenses.
Gnuaccounting - Gnuaccounting is a Free Java cross-platform accounting and bookkeeping application. Features
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!