I don't find bluetooth to be quick and reliable enough for this kind of use. I can sit down and type in my password a dozen times before a bluetooth discovers, pairs, handshakes, and does whatever else is needed.
Same with those bluetooth deadbolts for doors. I'll easily walk the ~30ft range of bluetooth, take out a key, and unlock the door, before it can connected and unlock.
There are a few apps that do this with usb thumbdrives. USB Lock and TokenLock are just a few I've read about.True, but I'm looking from more of a security aspect. I'm even open to a USB approach if there is one. Just looking to make my computer more secure.