One of these actually saved my life one night...

Phantom cell phone vibrations: an attempt at an explanation here.

While driving home late one night (sober, mind you), I came to a stop after getting off the expressway ramp.  Just as I was starting to pull into the intersection, my cell phone vibrated in my pocket.  I braked to pull the phone out of my pocket just in time to watch another car come speeding through the intersection.  If I had not braked, I would have been t-boned on the driver's side for sure.  I never saw him coming.  Of course, the  phone registered no call, no message, no e-mail, no text, no nothing; just a phantom vibration.  It is a mysterious universe we inhabit, thank God.

thanks glenn