I enjoy ProjectEuler.net and I would put it in that category. Within the first few months I was motivated to learn a number of excellent Python performance tips

I enjoy ProjectEuler.net and I would put it in that category. Within the first few months I was motivated to learn a number of excellent Python performance tips. I can't guess whether you find math puzzles as compelling as I do, but [the popular article about Project Euler in The Atlantic](http://www.theatlantic.com/technology/print/2011/06/how-i-failed-failed-and-finally-succeeded-at-learning-how-to-code/239855/ http://www.theatlantic.com/technology/print/2011/06/how-i-fa...) suggests that you don't have to have a history of enjoying math.