Rendon
I haven't read the Rolling Stone article on The Man Who Sold the War. James Bamford apparently wrote all kinds of interesting things about Rendon colluding in the propaganda run-up to the war.
Additionally, Rendon published a response to the article. They rebut everything Bamford said. They depict him as a liar. They are convincing, but, hey, that's their job.
On the other hand, there are some really fascinating documents on Rendon's website. Among the Public Diplomacy and Strategic Communications entries is one hefty PDF doc entitled, The Defense Science Board Report on Strategic Communications. After glancing at that alone, it seems as if all our worst fears about the "strategic communications" Republican media nightmare we've been living in for the last seven or eight years are very well-founded.
Until I read the article from Rolling Stone, this looks like the best piece I know of on the Rendon Group.