I was a member of a ski club in high school, about the time Power Bars first became all the rage. One thing I learned very quickly on the slopes was that unless you kept them close to your body, Power Bars (Snickers Bars, most energy bars) set up as hard as three day old concrete when they get cold. Eating them requires drooling on them long enough to soften them up. Pop Tarts, on the other hand, have a tendency to crumble into powder when you fall on them, but it is tasty, tasty powder and requires no drool.

I'm sure they're not nutritionally balanced, but they do fall into the "morale booster - tastes great" category, are pretty caloric, and if you eat enough of them, you might be able to make your own survival blanket out of all the little mylar pouches they come packaged in.