Summer means lots of running in and out of the house and nothing puts a damper on that like a sticky sliding glass door (OK, your Mom yelling at you to pick one, "In or out!" is kind of a damper as well, but I digress..).
Use this standard-in-every-household item to stop sliding glass doors from sticking.
Rub an old candle stub on the sliding glass door's tracks. The wax will lubricate the door, letting it glide smoothly.