The timing of Matt Simmons book in the top 25 is interesting:
Featured in daily top 5 on Jul 21, 2005 in spot #1
Featured in daily top 5 on Jul 28, 2005 in spot #4
Featured in monthly top 25 on Aug 2, 2005 in spot #2
Featured in monthly top 25 on Sep 1, 2005 in spot #21
Featured in monthly top 25 on Dec 7, 2005 in spot #22

The first 3, in the top 5, are when it was released. Then a month later as oil spiked to $70 in response to Katrina, now again as people are buying for presents methinks.

That is interesting.  Seems a rather odd Christmas gift to me.

Maybe sales are being driven by higher heating costs?