The Reflective Librarian has an interesting article on whether patrons should pay. One of the most ineffiecent things when working is asking clients for money. And the most confrontational.
Steve's article indicates that the library experience is enhanced by clients, when they are not fearful of overdue fines. Netflix has a policy of no over due fines and has risen to become the world's leading DVD rental business. Obviously, choice has assisted in making them no.1, but the no fine's policy obviously assists.