So you share an apartment and need to pay the bills but how do you go about this in an organized way? Bill Share is one idea to fix this problem. To use their own words you can “create receipts to divide shared expenses. Track spending habits with detailed statistics. Email alerts keep you updated on amounts owed. The group wall and messaging allow group members to communicate effortlessly. It's easy, simple and free!” Give it a try.
Disclosure: I have not used this myself because I have not needed it but the info I have found backs up that it is a usable and worthy site.