I wish I had taken more statistics courses. I learned the basics and have picked up a fair amount of the advanced stuff through self-study during graduate school, but I didn't realize during college how useful it would be.
I wish more people would take more computer science courses. Intro to Comp Sci is usually too basic to be useful. Data structures, algorithms, numerical/scientific computing are all useful in a large variety of careers.
I was looking at a discussion of what should be in a college curriculum, and as such discussions seem to go, there was a big list of things everyone should study, and some political claims about what's being offered but shouldn't be.
Instead, what do you wish you'd studied in college? What do you wish other people had studied in college? On the latter, do you think everyone should have studied it, or do you just wish more people knew about it? Approximately what percentage of people?
Of course, this doesn't have to be limited to college. People could learn the same things earlier or later.