I'm a PhD student in CS and I have a fair amount of background in mathematics. But it's been many years since I studied Mathematics in college. I would like to refresh and in many cases, understand the topics more intuitively, so that I could make pictures of the equations in my head when I see them. I already read suggestions including the Princeton Companion to Mathematics, but I think I'm looking for something different. I read many papers that include some mathematical material and when I do not understand something very clearly, I would like to go back and study that topic for some hours (or a couple of days). Do you know of some book/website/material like this?
Examples of things I liked in the past are some material in betterexplained.com, this piece on matrix (Understanding matrices intuitively), and this AMS feature on SVD (We Recommend a Singular Value Decomposition).
Edit: fair amount of background in Mathematics means: someone who does not need to start from the very basic, or need resources that are without formulas and numbers; has the amount of background a typical graduate student in a scientific field like Computer Science has, but not as much as someone in Theoretical CS has.