I would make the case for a gifted kid to take calculus, even if he/she was destined to be a humanities major or perhaps a science major. I think there is tremendous value in learning to think in the way that calculus teaches - fairly abstractly, with some very practical applications. I went all the way through multivariable calculus, and decided I wasn't as good at math as I'd hoped. I don't use any math in my profession, but I think it was valuable to learn the discipline.
Both of my parents actually took calculus last year at a community college (mind you, they're in their 70's) as a continuing ed adventure. They both thought they should take calculus before they passed from this earth, and neither had taken it in school. I got a great chuckle out of that.
