If you have to use them up to be at peace with yourself, use them in the winter. The heat they create will offset whatever heat source you use. Maybe not 100% efficient, but not too awful either.
You can also use them to provide a little bit of heat in places with pipes prone to freezing, ie utility room/basement/crawl space.
Use them in closets or rooms you really never go into anyway.
Or wait until you can no longer find them and sell them on ebay for ridiculus amounts!