An ounce of prevention...

In this case, I'm using a plastic cup of prevention. We have a chest style deep-freeze in our basement full of meat and fish, fruit and vegetables, and some foods like trays of oven-ready lasagna or frozen tamales. We always store the freezer full, using PETE (#1) plastic bottles of water to make up the empty space. But I was occasionally worried that the power would go out while we were away or that one of the kids would leave the lid open without me knowing (It happened... my kids, my aunt's house, sore subject.) My concern is that it will all thaw and refreeze without me know about it - exposing my family to food-borne illness.

Fill cup.	Here's what I've done. I took an eight ounce plastic cup (I used a kid's cup from a local restaurant.) and filled it with water nearly to the top.  I placed the cup in the freezer until it was frozen solid.  Then I put it upside-down in the basket at the top of the freezer.  In the event of a power outage (or other freezer disaster) the ice will melt as the temperature in the freezer rises, at least the ice will fall out of the cup at worst the cup will be empty. Since the cup of ice is upside-down, I'll know the freezer has been affected even if everything has refrozen.
Freeze water.	During a power outage, keep your freezer closed.  Don't give in to the temptation to open the door even once.  If it lasts more than two hours, you should evaluate the contents of your freezer when the power returns.  You'll need a food thermometer.  Anything that has been at 40 degrees or higher for more than two hours should be thrown away.  If food in the freezer is colder that 40 degrees and has ice crystals, you can refreeze it.  If you are not sure about an item, throw it away.
Place upside-down in freezer.	Food safety is an important issue everyday.  Conveniences like refrigerators and freezers allow us to have little concern for food spoilage.  When our normal routines are altered, however, we need to put a bit of thought and planning into staying safe and healthy.  One resource available to you is the USDA website.  They offer tips on food storage, thawing frozen food, and using dry ice in your freezer.

Thank God, I have never had a major power outage while I was not home to take care of things.  But I do still check that little cup almost every time I get something out of the freezer.