Startup Idea: Application for Tracking Debts among Friends and Family

Startup idea to develop a simple and essential iPhone app to monitor and manage money you've lent to your friends and family. The app should integrate with Facebook to send intelligent reminders about the owed money. Integration with Bitcoin could be an added feature.

My time is usually split between friends and family. But sometimes is hard to keep tracjng of who owes who money.

A software that allows me to monitor how much money I've lended to friend. Something simple, essential, for the iPhone ideally.

I would like an app thats integrated with Facebook and can intelligently remind each of them thru Facebook that they owe me money. Wouldnt that be cute.

A nice to have would be bitcoin integration, but thats neither world and it may be too soon.