Have you played Sudoku (Wikipedia: Sudoku) yet? My mother turned me onto it. She figured I would like it in part because I like math. Turns out there really isn't any math to Sudoku, but there are a lot of numbers and that can be fun. Sudoku reminds me a lot of Minesweeper, but it's a lot more fun, and you get several "A-ha" moments while playing.
I would play it more, but it just burns time in a big way (hint: great for flights!) and I've already got a huge backlog of stuff I need/want to do.