Hyperlite Mountain Gear insulated warming pouch for rehydrating freeze-dried dinners.
I like to heat my water and add it to the bag without suddenly being on the clock to hurry up and finish all my other camp chores and be ready to eat before it's cold and nasty. This thing weighs next to nothing, and I can make the water before I crawl in the tent and eat whenever I'm settled in and feel like it.
Also, not exactly a "carry," but I wish I had gotten a decent chamber vacuum sealer many years before I did.