Wouldn't it be great if there was a Facebook application that lets you track the things that you have lent to people (money, CDs, DVDs, anything)? You can link to the person's facebook profile so that you can just message them directly from the application when you want it back. You can even include the date by which they should return it as well and notify them when the date has been reached.
What do you think? I couldn't find anything of that sort on Facebook just now.
I would call it the Facebook "Lending Tracker"!