That would be cool, but I would be afraid of people trying to take my finger (maybe even the wrong one!). I'd rather just have someone take my keys like everyone else.
If I ever rigged up a biometric scanner, it would scan my entire body, including checking for heart-rate and EEG readings. In order to get in, I'd have to be present in full, alive, and not stressed out by an act of duress (calibrated to my normal level of stress during the pre scan, obviously.)
Aren't there situations where this could backfire? What if you just finished running around the block and need to get inside? What if you just finished running around the block away from rabid dogs and need to get inside FAST?
Perhaps this wouldn't be a good choice for a front door to a regular home. Perhaps the entrance to a secure facility, though, where time would never be an issue (with a keycard and a vocalized passphrase as well, for additional factors.) Not a nuclear launch silo, but perhaps a top-secret research facility.
