If Shenon's book was your introduction to the simple fact that the 9/11 Commission failed in its mandate on several levels, then you are probably unaware that serious criticism of the 9/11 Commission was entered into the Congressional Record of the 109th Congress. This criticism was the result of a Congressional Briefing conducted by former Congressional Representative, Cynthia McKinney of Georgia. (McKinney is currently seeking the Presidential nomination for the Green Party of the United States.)
The briefing was held on July 22nd, 2005, subsequently broadcast by C-SPAN, and studiously ignored by the corporate press. A comprehensive collation of the briefing has not been made available online, but thanks to the magic of YouTube, I have chopped the most pertinent testimonies from that day into neat 10 minute segments that are easily digestible for the busy internet surfer. You may have seen some of the footage from the briefing in the documentary, "Press for Truth", where Lorie Van Auken talked about her husband's fate on 9/11. Beyond that, not much of this footage has been circulating on the net.