If this is a serious thing by some nutty anti-American whoever-you-want-to-imagine, then it is one of the most perturbing and carefully done threats that's ever hit the internet.  The video first surfaced on YouTube, and...

"Freakonomics" co-author Steven Levitt got the blogosphere in an uproar after he asked readers to submit how they think terrorists should attack America. The argument is that getting these ideas out in the open helps us...