Freezer Fail Detector: Here's a simple one: what happens if your power goes out while you're on vacation? Well your food will thaw, then go bad, then refreeze, and you'll be none the wiser when you go to eat it. The freezer fail detector is just a jar filled half-way with water then frozen on its side. Put the jar upright and glance at it whenever you open your freezer. No more salmonella!