I had a chance to play with my new pot cozy recently.  A cozy is a light insulator fitted to a container or pot.  I'm using one that came from AntiGravityGear.  The idea is that you heat up your water (or whatever) then mix in your dried food and put the cozy on.  The cozy keeps the pot hot much longer than it would normally.  You can rehydrate food using a fraction of the fuel.

My cozy worked surprisingly well.  I was making some quinoa. Normally, it has to simmer for ~15 minutes. I got the water and quinoa boiling, let it simmer for around five minutes, then into the cozy.   Ten minutes later, I had a hot, fully cooked meal.  A cozy weighs a few ounces at most.  The fuel savings makes it well worth carrying one. 

Just remember, you can't expose the cozy to direct heat.  And they aren't the most durable items; a little caution is a good idea.  If you're interested, AGG has a bunch of cozies for different size pots.  Or, get detailed instructions on making one here.