BillMonk is a free service that keeps track of shared bills and money lent or borrowed. Let’s say you go out for dinner with a couple of friends and decide you will pay the whole bill and have your friends pay you for their portion later. Log in to BillMonk, enter your friends’ email addresses (no spam!) and the amounts they owe you. They’ll get an email with the details, and have the option to settle up in person or by using Obopay, a service that lets you send money using your cell phone, similar to Paypal.

I have not tried settling up using Obopay yet, but have been using the rest of BillMonk’s features for about four months now. It’s a simple way to keep track of who owes what without having to do any hounding. I don’t think I’m alone in saying that settling up at the end of a meal is no fun.

Some other neat BillMonk features:

• Itemized bills
• Recurring bills (rent, for example)
• Ability to add comments and tag bills
• “Library” feature which provides a way to keep track of things you’ve lent and borrowed
• Add bills by phone