IOU (I owe you) is the most developed and feature-rich debt manager app for web, Android and iOS. Very simple and very powerful. Syncs with web app (http://ioutool.net) and among mobile devices.
With options like recurring debts, payments and notifications you can keep track of loans, periodic payments, bills and personal debts all in this single app! Syncing to ioutool.net allows keeping and editing your data on different devices and in web browser and share debts with your contacts.
-Borrow/lend things and money
-Clean and simple interface
-View by debt direction or debtors
-Email and text reminders
-Recurring debts and payments
-Notifications for overdue debts
Windows Phone 8 version is on the way.