A criticism of Obama on a planned windfall tax on oil companies:

These add up to what you could call the stock Democratic response to tough times. They're not necessarily bad ideas, but they're not what you could call new or transformative either. Obama throws in a few populist panders -- he favors a windfall profits tax on oil companies (which could discourage investment in new energy resources)...

This would be sound logic if the oil companies were investing in developing new energy resources.  The problem is that, for the most part, they aren't.  What they are instead doing is investing tons of money in dividends and stock buy backs.  If they were actually investing in developing alternative energy sources or were discovering as yet unknown oil fields, we'd not have a problem.  The trouble is they have little interest in alternative energy and those unknown oil fields, for the most part, don't exist.

So rather than wishing and praying for them to invest in an energy source that, in the end, would be competitive against their existing product, and bad for their bottom line, we take the initiative ourselves.  We take the money out of Exxon, etc, and put it into developing real energy alternatives.  It is also worth noting that the windfall tax that Obama is suggesting would have out clauses if the companies invest in this themselves.