I saw a prospectus at a recent gun show; the local safe maker was planning on having an optional Bluetooth reader that would be keyed to your cell phone. Approach within 3’ of it, and it unlocks for you if you’re carrying your cell. (And if you’re going near the door, you’re going to want that cell phone on you, right?)
That's not a bad idea. Of course, if it's bluetooth, you could pair it to a PDA or even a key fob. I have a full wall of bookshelves on one wall of the living room adjacent to the door -- I could easily stash a wireless "key" somewhere I could get it in a second, but an intruder couldn't find it in a timely manner.