A footnote to the blog (10th June 2008) about modelling demand for swimming.
A major cereal company in the U.K. (the name begins with "K") offered vouchers for free swims on its packets. As a promotion, it has been very successful. But the swimming pool in Exeter has had to restrict the hours when the vouchers can be used. It isn't really a rationing of use, simply a way of allowing the fee-paying swimmers time to enjoy their swim and concentrating the use of the vouchers to times when fee-payers can stay away.
This is an interesting solution to a demand problem. It has obvious links to revenue management.