Bruce Schneier explains how easy it is to get past security and fly on a plane even if you're on the supposed "no fly list"

Buy a ticket in some innocent person's name. At home, before your flight, check in online and print out your boarding pass. Then, save that web page as a PDF and use Adobe Acrobat to change the name on the boarding pass to your own. Print it again. At the airport, use the fake boarding pass and your valid ID to get through security. At the gate, use the real boarding pass in the fake name to board your flight.

His article on why the no-fly-list and photo ID checks are useless against terrorists here.