Nathan Seidle. of Sparkfun, is on a campaign to create a keyless life for himself. One of his last locks to join the 21st century was on the door to his Mazda:

I hate keys. I am on a mission to dispose of them all. There is currently a key pad to enter the SparkFun building, a key pad on my home, and RFID to get into the interior rooms at SparkFun. It is my goal to get rid of the last key in my pocket, my Mazda key! I combined the Nike+iPod device and my key fob, with an Arduino Pro Mini, to create the iFOB.

iFOBing A Mazda