Two really good pieces about how unbalanced taxes have gotten between the rich and middle class. The first is by Robert Reich, and can be found at Salon. The second is by Joseph Stiglitz, and can be found at Vanity Fair (in one page).
Both are must-reads, if you're concerned about where this nation is heading. The second one is particularly important, I think, as it ties in a couple of factors I hadn't previously considered. In particular, why we can't seem to get out of any of the wars in which we're currently involved.