Most people have heard that if you put a sealed envelope in the freezer, you can then slide a knife under the flap to open the envelope and it can be resealed. The freezer can come in handy in other ways, too!
To remove old wax from a glass candle holder, place the candle holder in the freezer for a couple of hours. When you take it out and turn it upside down, the wax should fall right out. I haven't tried this with a metal candle holder yet, but it definitely works for glass.
Also, you can extend the burning time of a candle by leaving it in the freezer at least 3 hours prior to lighting the candle. (Of course, don't light the candle in the freezer. That's just silly.)
If you're in the middle of a big painting project and have to stop for the day, or even just for several hours, instead of rinsing the paint brushes out just so you can get them dirty again the next day, put them in gallon Ziploc bags and stick them in the freezer. The next day, or whenever you get around to finishing the project, pull the brushes out of the freezer and let them thaw for about 20 minutes. Voila! The brushes are ready to use again, and you don't have to worry about water in the brushes!
Leave a section of newspaper in the freezer and change it out once a week. Newspaper absorbs odors very effectively. If you have to store fish in the refrigerator, cover it in newspaper to keep the smell from lingering in your fridge.