@Steven L: "How exactly do you propose to do this without *at minimum* doing the sort of things that the NSA has been doing?"
TSA has to defend against 2 sorts of attackers:
1) Organized terrorist cells planning an advanced attack. Intelligent and funded, these sorts of threats spend time planning, plotting, and communicating. We must depend on advanced intelligence to thwart these attacks, because by the time they get to the airport, it's too late. TSA is great at making a show of defending against past threats (see: body scanners, liquids, shoes - all reactionary measures) and terrible at actually preventing them. The key point is that these threats will not be stopped at the airport, regardless of how much money we keep dumping into the TSA. Increased checkpoint technology/screening/delays are not the answer; intelligence is.
2) The lone wolf/renegade/mentally deranged. Operating alone and without much of a plan, this sort of person cannot be predicted, but can be stopped with simple metal detectors and x-rays searching for guns and large knives.
There's no middle ground, and thus no need for anything more than x-rays and metal detectors at the checkpoint. Even ID checks aren't necessary. The way to speed up checkpoints is not with a better line, it's by removing the reason for the line in the first place.