Here's an idea whose time has come: self adhesive visitor's passes that invalidate themselves. The underpaid receptionist/security guard simply applies a protective film to the badge when handing it over: after 24 hours, the smiley face will appear. My only complaint? The graphic is counterintuitive. These products have been designed for schools. Someone wandering around with an expired pass shouldn't be identified with a happy face - it might confuse the kids (or your simple-minded coworkers).
They should be identified with something a little more explicit.
Thanks to bookofjoe for the pointer.
Comment from Peter Shankman after the jump. These have been in NYC schools and offices for years - they turn into giant red "EXPIRED" badges in a set period of time... 2 hours, 10 hours, etc.
I've always wanted "GET OUT OF MY OFFICE" badges I could just put on a visitor, no waiting for it to change at all.