I think there's a mod for cold bags, but how about small containers (think a serving-size) that can be filled with soup and stew and other hot foods to keep them warm longer and be better on the go. Think it would be great to make some stew in the morning and eat some before going out, but also taking some with me for the day that would stay hot for a longer period of time and thus provide more happiness than when cold.
In fact, hot water in a container could also be useful if there were packages of freeze-dried meals. Something like a sporting goods/outdoor store that has all the typical outdoor gear, but also packages of freeze dried meals that are non-perishable but provide more variety and nutritional values than your standard canned goods.
