My room mate introduced me to this web app for maintaining the room expenses and it does what it promises to do with ease.
Its web 2.0 too also so everything is done through clean ajax calls.
http://www.buxfer.com
One less thing to keep track off..
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Hi,
You might also be interested in Short Reckonings, which strictly focuses on managing group expenses, with a very trivial and fast Web 2.0 user interface. No need to register or invite people. And it calculates the fewest number of payments needed to reconcile the debts.
http://www.shortreckonings.com
Enjoy!