Whether you're sharing bills or going Dutch, paying someone back in a world full of debit cards can be a headache. Sign up for this service that lets you send person-to-person payments via your mobile phone. It's easy to use and cuts down on any IOUs.
NOTE: *If you want to add a new person with their bank account information, you will need to do this inside of Online Bill Pay. Simply click on "Popmoney" on the green bar and then "Contacts" and select "Direct Deposit" and follow the instructions.