Some info on Contango and Backwardation.  I'm going to steer clear of any financial instruments that invest primarily in futures because Contango and Backwardation can seriously impact the instruments return and could crush you if you are not careful.

The first article is a discussion of contango and backwardation as it relates to USO and OIL, two oil futures funds.

http://www.marketfolly.com/2009/01/how-contan...s-and.html

...and some definitions

http://en.wikipedia.org/wiki/Contango

http://en.wikipedia.org/wiki/Normal_backwardation