Maryland decided that to be a college graduate everyone should pass a math course with a prerequisite of Intermediate Algebra (or high school Algebra II.) Assuming that a college graduate passed Intermediate Algebra, what else should he know in mathematics?
If I were to pick one course, it would be statistics. This is not an attempt to garner more students, because I rarely teach statistics, but a belief that a basic introduction to statistics is the single most useful mathematics that can be learned in one course. This does not allow people to become statisticians, but gives them some understanding of results that are thrown at them regularly from many sources.
I would also make How to Lie with Statistics required reading for every high school graduate, but that will never happen.