The smell data is coming. Several entertainment companies are jousting patents over home theater options for adding odor (or odour, for those outside the US)... Disney already has several attractions which inflict smells on the visitors. My sons thought the Stitch escapes attraction was funny; I personally didn't enjoy having an animated character pass gas in my ear while strapped into the ride's restraints.

I'm thinking that the smellometrics might be the way to go, but it has the verification problem as any other biometric that has to be digitized, transmitted and compared with the centrally-maintained authorization data store. That said, I know that your dogs know who you are in the dark, regardless of what other smells you've been involved with recently (with a few exceptions: skunks, cayenne powder, gasoline, etc). If the smellometer can "tune out" the distractors of food, alcohol, perfume, etc, and focus on the unique phermonal-type scent we each have...

Amusing science fiction opportunity: "The odor sensors on the security door can't tell whether that guy doused with gasoline is the right guy or not... but he looks like his picture." Heh.