An IOU often ends up mere lip service to the fact. The situation often goes something like this: X owes Y for dinner and taxi fare. X holds out, waiting for Y to forget, or perhaps it goes unmentioned, and the whole business is goes to naught. To prevent such lapses in memory, there’s What.io. What.io provides an easy, online way to keep track of all those IOUs you’ve got lingering in the air. How it works: first jot down a description of what you owe along with the person’s name you owe it to using the form at the top of the page; click save. Clicking on the you toggles between them or you to specify who owes what. All IOUs you’ve created are only visible to you; privacy settings may be customized once you’ve registered. You can edit your IOUs to mark them as pending or completed. Entering a Facebook ID or email address will result in the IOU being sent out to that user. There’s also a print feature, so you can print out and post your IOUs in plain sight.