Keeping track of small debt between friends, both ways

[Pedro Emílio Machado de Brito]

What is the recommended way of keeping track of debt between friends?

I owe Bob $10, I pay his dinner, $15, now Bob owes me $5. I'd like to
keep track of this in a *single* account, not two separate asset and
liability accounts, one for when people owe me and the other for when
I owe them.

What I'm using right now is a top-level placeholder equity account,
with equity sub-accounts for each person, but I'm not sure if this is
the best way. It doesn't feel right to put this under Assets or
Liabilites because it can represent either, depending on the sign of
the balance.

Cheers,
-- 
Pedro Emílio Machado de Brito

Ciência da Computação 2012 - Unicamp
Coordenador Financeiro - Centro Acadêmico da Computação (CACo)