Home Finance System / Bill Splitter

Hi - I share a house with two other people and have set up a spreadsheet in the past allowing me to track bills (rent, electricity, phone, etc) including who paid what and how much each person owes in total. Unfortunately I had my laptop stolen around christmas and lost my spreadsheet with it. :( I was about to set up a spreadsheet again - but since I've started getting into learning PHP - and have recently set up our home linux server - thought that it would be a lot more exciting / functional to have a system running on the server that would allow each person to log in, track the current bill status, pay a bill, enter new bills, etc. I was wondering if anyone knew of an existing system that would do this for me, or if anyone had ideas as to exisiting systems that came close to the functionality I'm after - that I could tweak. I'd also be interested in hearing from anyone who would be interested in such a system, or developing one, or collaborating on a PHP newbie on putting together such a beast. Thanks! - dan.