Unlock your car from the outside!

This only applies to cars that can be unlocked by remote button. Should you lock your keys in the car and the spare keys are home.

If some one has access to the spare remote have them telephone you on your cell phone.

Hold your (or anyone's) cell phone about a foot from your car door and have the other person press the unlock button, hold it near the phone.

Your car will unlock. I tried it and it works. Saves someone from having to drive your keys to you. Distance is no object.