Go to Walt Disney World, they use biometric finger readers at turnstiles to help catch guests who share (non-transferable) admission tickets. Disney's biometric readers scan coarse characteristics like length of fingers, not fingerprints. Airports would probably need something more detailed.

How much would it cost to build a wall as stout as the Great Wall of China along our borders? People entering illegally have wire cutters to get through ordinary chain link fences.

Disney hints:
http://members.aol.com/ajaynejr/disney.htm