See what I did there?
I caught this over at Engadget, and I want this. Yesterday.
Guy has programmed a "secret knock" that will allow this gizmo to unlock his deadbolt, which is nothing more than a circuit board, PVC pipe and a little piece of metal (aka "the party") that turns the deadbolt. Knocks are programmable by the user, and incredibly simple to do.
You can knock slowly, as long as your rhythm is down, you're golden. However, add in an unnecessary knock or mess it up, you gotta start over.
Really awesome idea, but it's something you'd have to program a new knock every day - or, godforbid, more than once a day - just in case you're neighbors hear you knocking away, trying to remember what the secret knock is today.