I may echo some already posted, but since I have a 6 year old boy, I've got some experience with this...
How to handle a weapon, any weapon. When my son was 2, he knew to turn a knife around butt first before handing back to me (or anyone else). Same with a screwdriver. He's had his own machete for a year now.
The difference between Phillips and Standard.
Never, EVER point a gun at anyone, ever. My whole family got a sudden lesson in this when I had a 12 guage that I thought was unloaded! (Hole in the roof, no one got hurt.)
How to hit a baseball.
How to dribble and shoot a basketball. Even if no other kids in the entire world want to play, you can always shoot baskets by yourself.
How to throw a spiral football, and how to throw a frisbee.
How to swim. How to dive. Was working on this this summer, but it was too cool to go swimming too often.
How to light a fire. (we worked on this one just tonight)
How to talk like an adult, no matter what age. We never "baby-talked" our son and to this day still get compliments on how easy he is to understand (and talk to).
How to hold the light while dad works on the car (because his son will have to hold the light in his time)
How to drive (working on this with my 14 year old daughter)
How to change a tire (was working on this last week until I broke a lug off and sent my son inside before he started hearing "car-repair" words)
How to use a computer/mouse/keyboard. I know they learn it in school now, but it doesn't hurt to pick things up at home.
How to dial a home phone and cell phone.
How to check out hotties (I'm working on this but girls are still "icky")
How to be polite to everyone.
How to ride a bike (was working on this until we moved into a new house that's on a hill)
How to be safe around ladders, power tools (mowers, chainsaws, drills... ) safe around cars on jacks, safe with fire, safe around water, safe near the road... That list will never end.
How to tie knots (haven't done this yet as I'm not good myself, but it's on the agenda)
Same with how to read a compass.
How to mix concrete.
How to find books in the library.
How to pump gas! Haven't seen this one listed yet, and it can be tricky the first few times if you've never done it.
How to shave. My father laughed at me when I was trying, and it kinda hurt.
Mom does all the cooking, and he's already picking some up from her.
How to enjoy alcohol responseably.(to re-word that - How to be responsable around alcohol)
I did, or would do, most all of these with my daughter, but we went through some rough times and only became friends a few months ago. Still, I never miss a chance to teach her a skill that may come in handy. Couple weeks ago she learned a basic windmill (inside info for the thread starter!
)
Grim/Don
Proud father of Zane