I cannot drive to work if I forget my keys.
However, I have following idea.
A cell phone case with an imbedded radio frequency chip that communicates with your key chain. The purpose of the device is to alert you if get too far away from your phone. This two way radio will not only help you locate your phone, but you can use it to locate your keys as well. You will be able to preset an approximate range boundary which will cause the case/keys to beep when they are too far apart. If you are close to the phone but can not see it, you can make the phone beep by pressing a button.
