Not art, but beauty. Mathematics is full of beautiful surprises if you know how and where to look. Even a circle, while fairly ordinary, could be considered beautiful in its simplicity. While I generally use fractal programs to create my artwork, I do occasionally dabble with other programs that present mathematics' visually appealing side. I have yet to incorporate their output into my art, but that's not to say that it won't happen some day.
Many screen savers use mathematics to good effect.
Both are fascinating to watch. One of my favorites, though, is a shareware program by P. D. Grengs II called Special Effects . A well done screen saver for fractal enthusiasts is Damien Jones' JuliaSaver , which displays real-time morphing Julia images in full screen mode. Polyhedra and art meet at George W. Hart's page here . Finally, if you're like me you might also find John Conway's game of Life fascinating.