Alex has a nifty way of using gmail filters to automatically create a Waiting For list:
Whenever he requests something he wants to keep track of, he also sends a blind carbon copy to himself.
THEN
He creates a filter that says:
"Whenever gmail receives things sent from his account to his account..."
THEN
"...make those things skip the inbox and get labelled "@WaitingFor".
Email labels, like sports cars, I don't normally like. But I think I will take this one for a testdrive.