There are a few other assorted courses that I've found useful in the field.
Communication. No matter how good your high-level designs are, you must communicate your vision to the rest of the team. Having solid communication skills is one of the most important aspects of being a designer. If your school has a class in active listening, take that too -- designers tend to receive lots of feedback from their team (mostly on how much their design sucks :-), and being able to listen effectively and deduce the real design problems from someone who isn't a designer is a great skill to have.
Microeconomics. Really, anyone that wants to work for a company of any sort should understand the basics of supply and demand. Like it or not, game companies are businesses and they therefore need to make money if you want to continue receiving a paycheck. This course will prevent you from saying embarassing things in company meetings, like “we should make our game engine open-source and stop charging people for it, we'd get more players then.”
Women’s Studies. Currently, the game industry is really terrible at dealing with women. First, it’s lousy at attracting women to the industry; the average game company is about 10% women, and it’s even worse if you just look at game designers. Second, it’s not so great at marketing to women; the number of female gamers is growing, yes, but if you look at game ads and game magazines (and some games, too) you still see chainmail bikinis and the like. Game developers (especially male ones) need to understand some fundamental truths about women if we ever want to make them feel welcome. I sincerely hope that some day, this problem will be fixed and I’ll be able to remove this course from my proposed game design curriculum.