I think discrete math is another tragically under-represented math topic that would be of more benefit to most people than calculus. Within that broad topic, I'd single out the essentials of logic, set theory, combinatorics, and basic discrete probability: those are the sorts of things that most people, regardless of what they do for a living, could profitably use to do their jobs better from time to time and to solve the problems that day-to-day life throws at them.
This guy says that the problem is that high-school math education is structured to prepare people to learn calculus in their freshman year of college. But only a small minority of students ever takes calculus, and an even smaller minority ever uses it. And not many people ever make much use of pre-calc subjects like algebra, trig, or analytic geometry.
Instead, high-school math should be structured to prepare people to learn statistics. Probability and basic statistics, he argues, are not only more generally useful than calculus, they are also more fun.
I have to agree with him. What do the people here think?