I often supplement the FSRs with a Flameless Ration Heater and a hot beverage bag in order to have a quick cup of coffee.
I picked up a Trekmates Flameless cook flask for about $8 on sale last week. It should be handy for the occasional hot cup of hot chocolate/Soup etc in very difficult conditions. Flameless high heat packs still cost around a buck a piece though.
http://www.youtube.com/watch?v=LPt35oJ5-kk