Quick tip for refrigerator art: Decorate with magnets instead of stickers. Those cute stickers with adhesive backing look great until you try to get them off. Then you're left with a sticky residue that isn't so attractive. The good news is you can remove the stuff fairly easily with an oil-based liquid.
Remove as much of the sticker as you can -- you probably won't be able to get off all the backing. No matter what product you use to remove the sticky residue, rub it on the spot with a cloth or paper towel. Let it sit a few minutes, and clean it with a sponge or scrubber and soapy water. Wipe down with clean water and spray with glass cleaner if desired. Dry it, and you're done.
Use something you already have in the house to remove the residue from a sticker. Vegetable oil, mineral oil and baby oil all work. A nice-smelling alternative is eucalyptus oil, which you can also use for other household cleaning tasks (see Resources below).
Use a natural cleaner such as Goo Gone. It's also great for removing other "accidents," from chewing gum to crayon marks.