We have run the Mr Buddy heaters in a tent (Bomb Shelter and Cabelas 6-man) and they keep you warm. I like it a bit cold when I sleep, so generally don't do that unless it is really cold. It comes with complications of course, in that you need to provide ventilation. It is pretty nice in the morning to lean out of your cot, kick on the heater, and then wait 10 minutes to get up into a nice warm tent. If you want to get really fancy, cover up the high traffic areas of your tent with
These Keeps the feet warm. Hey, luxury is underrated.
Lots of good tricks mentioned already. Nalgene full of hot water in the foot of the bag is one of my favorites. Try to not be cold when you first get in the bag, whether that means 20 jumping jacks outside the tent or having a heater.
Then of course, there is whiskey.
