Alex, that is a great site you have, with more math-oriented fiction than I ever knew about. I found it through a recent comment on Slashdot. Other things I've planned to do this evening... all gone out the window now! I mean that in a good way, of course.

One book I don't see mentioned - Macroscope by Piers Anthony, published the early 1970s. I read it in high school, and it had an influence on several of us smart science-oriented kids. Two reasons, at least, it could be considered math fiction:

1. A key point of the plot how something that could be considered an educational video from unknown cosmic sources causes insanity/brain-death of some of Earth's finest intellects. The honest educational video part of it introduces a source of galactic knowledge free to all (iirc) - sort of like wikipedia but one-way and better quality. It is overlaid by a "Destroyer" signal which is a major thread in the plot for the rest of the book. Both are mathematical in nature - the universal language among intelligent beings, as is popular among speculators in science to believe. Simple shapes, equations, etc. growing into sophisticated language.

2. "Sprouts" - a paper-and-pencil game for those who love topology. My classmates and I played far too much of this during class.

It also contains the only sensible description of astrology I've ever read anywhere, but that's not math. And some wild engineering, and an interesting way to travel at high-G.

Even if not the strongest example of math fiction, it's certainly as much as many other fine books and movies in your database, and I urge you to please add Macroscope.