When we use a common good, we cause the most expense and anger when we all use it at the same time. An idea that is now being tested in several places is to convince a small percentage of people to deviate their usage of the good from this popular time points. It is generally agreed that in many cases, a change in the behaviour of very few people can already relieve a system of much pressure.
The current consensus seems to be that the system operator should pay people for that. If someone actually has the flexibility to deviate, the opportunity to earn or save money might make him actually identify and use it.
I see this in electricity markets, where demand peaks can maybe avoided by convincing a couple of devices to stop operating for a while and also in traffic management: The city of Utrecht plans to pay a commuter €4 per workday if he doesn't use the highway A2. They will have to devise some solutions where they film the numberplates of passing cars, but building new streets might be much more expensive (not to mention how much trafic jams hurt the economy and the mental wellbeing of commuters).
This can be a very effective way towards more efficient usage of common goods - but there are hurdles like the increasing hunger for usage data that comes along with it. Not many people will like that and we will need to talk about this. The good news is that if the mathematicians are correct, not everyones flexibility is needed.
Update: The Netherlands now plan to tax highway usage for everyone via satellite by 2012 (like the Germans already do for trucks). This system is more flexible, but also harder to accept.