In a surprising (to me) move, England is proposing "pay as you go"" driving. The fees would range from a minimum of 2p per mile to £1.34 for high congestion zones. (In USD, these amounts range from four cents to $2.50 per mile.) The government is planning to roll out a similar plan in 2008 for trucks first.
From The Financial Times :
"The transport secretary unveiled his department's latest thinking on road charging in a speech to the Social Market Foundation. Such schemes could cut congestion by almost half with only four per cent less cars using the road, he said."