For whatever reason this thread that I started was locked and therefore, someone started a new thread called debts answer earlier this month. Under that thread, lots of good comments. My favorite was one from Landerson:
"I see at least two choices. Use an @Agenda item with that person's name on it and the details of what is owed to them.
or another choice... I keep a list titled IN/OUT - it has everything listed in one place that I have on loan to others ...
OUT - "DaVinci Code" - to Kelly - 3-14-08
OUT - "Pirates of the Carribean" dvd - to Joe - 4-1-08
and for things I have on loan from others...
IN - $4 from Bill - borrowed on 9-1-07
IN - "Gone with the Wind" from Jeff - borrowed 11-13-07"
I went with this system and implemented @In/Out context. It works really well for me right now.