al Qaeda's most important accomplishment was not to hijack our planes but to hijack our political system.Edit (2014-09-17): Sorry about turning off comments for this post, but somehow it got popular and spammers started deluging it with comments linking to their own stuff. Weird.
$200 Million per Arrest
Congressman John J. Duncan Jr. has a fantastic article on the uselessness of air marshals. Best quote: