If we're not living in a post-apocalyptic world where there are only a handful of survivors on the entire planet, two un-mentioned skills I've found very useful are the following:
swimming
unarmed fighting and crowd/person control
Strange as it seems to me, some people actually couldn't swim to save their lives, much less the lives of others. Also it's good to know how to handle yourself among larger waves.
As for the unarmed part: most confrontations can be resolved with talk and minimal physical contact. Learn to use the fence (both, psychological and and physical, social will develop over time when you stay in one place longer), it will save you LOADS of trouble if you have to deal with people some times (most of us haven't the luxury of staying in our forts 24/7). This is VERY simple. Study what the experts (e.g. Geoff Thompson) have to teach. You can learn his most valuable lessons from a book (they haven't much to do with actual fighting although they are pure self-defense brilliance). Learn the color codes of awareness, learn about adrenalin etc.
Then learn a few techniques on your feet, on the ground, and you're good to go, ready to survive most altercations with drunkards and other people who might consider harassing you or yours.
The third important thing isn't really so much a skill as it is a state of being: be physically and mentally fit. Can you imagine that you can get a loved one killed by being obese? Think about getting stuck in a burning building, you fall down and break your leg. Your father/brother/wife/even fireman might die trying to drag your 400lbs lardy ass out of the burning building.
In addition, being out of shape/weak/obese increases the risk other physical ailments and also inhibits you from being an efficient savior in case You have to drag someone (God forbid, a 400lbs man!) out of a burning building.
It's not just for fires: you might have to swim 500 yards to save a drowning child or you might have to sprint a half-mile, running away from a mob of rioters, whatever.
Bottomline is, you are of more use to yourself and to your loved ones if you're fit and heatlhy.
Just a few thoughts.