A reader who wished to remain anonymous suggested to me that if I want to go long on oil (so as to make its price collapse and end the suffering), I should take the route in plain sight: buy the ETF with ticker symbol OIL. Apparently, its value stays very close to 1.68 times the current spot price of oil. In fact, since neither Yahoo nor any of the finance sites I go to actually let you chart the history of the price of oil, you should use that chart when you want to compare something to oil's price history.
(The reason is that the quoted price of a barrel of oil is actually the price for a delivery in the near future, so expanding the time history of that just gets you the price of a briefly-traded security. But when you want the *history* of oil's price, you don't want a plot of the price of an "August 08 delivery"; you want a plot of "August 07 delivery as valued in July 07, September 07 delivery as valued in August 07 ...".)
Why you'd want to remain anonymous about that, I have no idea. :-/