http://finance.yahoo.com/echarts?s=gbpusd%3Dx#chart3:symbol=gbpusd=x;range=20010911,20080616;compare=eurusd=x;indicator=volume;charttype=line;crosshair=on;ohlcvalues=0;logscale=on;source=undefined
Since September 11th 2001 the US dollar has dropped between 40% and 60% of its value, and a large portion of the run-up in oil prices reflects that change; if the dollar was worth what it was in 2001 we'd be looking at an $85 to $100 barrel of oil, and a $2.50 to $3.00 gallon of gasoline. From there you can associate $20 to $30 in the increase in demand/lack of supply, and potentially another $20 to $30 due to speculation.
In other words, oil prices would be far more reasonable if the federal reserve wasn't devaluing the dollar to bail out investors (small and large) from their risky investments in the dot-com bubble and the real-estate bubble.
