Living with roommates can save money because you get to split the bills, but the actual bill splitting can be quite a hassle. BillMonk can help with that. Whether it's monthly bills with the roommates or a group vacation, this online tool makes keeping track of who owes what pretty painlessly.
First thing's first: the service is free. Registration just requires your name and an email address, and then you can easily keep track of the cash you owe or other people owe you. It tracks several expenses and then calculates how much everybody needs to pay to settle up. The system makes it difficult for anyone to flake on their share so nobody finds themselves on the short end of splitting bills.