Nate, a guy who absolutely detests keys, has come up with a fun hack that transforms a Nike footpod and an iPod into the "iFOB"—a unique RFID remote that automatically unlocks his car doors from far away for a completely keyless entry.
For this hack, you'll also need a Adruino Pro Mini, a USB cigarette adapter, a multimeter, a JST connector, a case, some aluminum foil, and a tiny bit of car knowledge so you don't completely mess up the security system. Because this particular iFOB hack will automatically unlock your car doors from 50 feet away, Nate suggests "sabotaging" your antenna and wrapping the hack in aluminum foil to create interference. This cuts your reception down to 20-25 feet, so with a little tinkering with the Arduino board, the hack is able to automatically lock and unlock itself periodically every 10 seconds before you actually get to your car. [SparkFun via HackADay via GadgetReview]