Serendipity: on the day Washingtonian posts my article arguing for using variable congestion fees to reduce traffic, Treehugger posts a great graphic on what car commuting really costs.
One of the reasons people hate the idea of paying congestion fees is that they are often pretty bad at calculating what traffic really costs them. But time is money, as they say, so congestion fees are offset by the time savings you gain. Plus, the revenue can be invested in transit improvements and options that are currently paid for with a gas tax. Think about it.
Anyhow, if you really want to save money, this graphic really drives home the key point: try to live near your work! The Suburban Dream is very expensive.