Every physics major knows he needs to take a bunch of math courses. But there are so many offered at my university its making my head spin! I've taken (aside from lower division linear algebra/calculus/DEQ) real analysis and abstract algebra so far, and I've tentatively decided to aim for differentiable manifolds and dynamical systems as well. I know that I'll be able to take more than those two, so I'm looking for some advice. Whenever I ask this question people answer with "Well, what kind of physics do you want to study?", and I don't have an answer to that yet. It would be pretty useful to know which areas of math are most useful for some common/major areas of physics, both theoretical and experimental.