These charts are some of the best I have seen which illustrate how our current economic contraction compares to past eras. The chart comparing the Dow to commodities is particularly interesting, showing that massive drops in commodity prices have accompanied every major depression since the 1700s. The charts inverting commodity prices are also very intriguing, by illustrating quite graphically that what has really been happening lately is an appreciation of the dollar.
Since the summer of 2008 we have seen one of the most severe crashes in commodity prices ever. These charts show how big price corrections in commodities have an uncanny correlation to downturns in stocks, and the economy.
By the way, Elliott Wave International (the group that put this data together) is my favourite bunch of analysts anywhere. They have been about the only ones out there calling for a deflationary bust, even during the height of the bubble.