Both of these relate to freezers and power outages/loss of freezing for whatever reason.
1) I learned this one the hard way: don't make my mistake! If you have an upright freezer, purchase plastic bins that fit on the shelves and put your frozen foods inside the bins, not on the shelves. That way, if your power goes out (or if it doesn't go out, but somebody whose name will be nameless accidentally leaves the door open a crack and all the cold leaks out) and everything inside melts, it will melt inside the bins, greatly facilitating cleanup. The alternative being, of course, cleaning disgusting smelly thawed raw meat juice out of the bottom of the freezer and off the basement floor--just ask me how I know about this. There isn't enough bleach in the world to eradicate that odor!
2) Wash out large plastic drink bottles (soda and juice bottles are ideal) refill them with fresh water, and freeze them. Fill any empty spaces in your freezer with these bottles. Should the power go out (or someone leave the door open, ahem) these very large solid non-messy 'ice cubes' will help keep the contents of the freezer cold for an extended period. And, of course, once they thaw, they are another supply of water for those poor benighted souls such as ourselves whose household water pump does not run without electricity.
This has been a public service announcement. :) Anyone have any other tips to add??