I'm thinking about just getting a variety of different puzzle type books and seeing how that goes. Right now that list includes Math Perplexors, Venn Perplexors, Pentomino Puzzles: 365 Teasers to Keep Your Brain in Shape, and some kind of matchstick puzzles (if anyone knows of a good one please pass that along). Can you think of any other kind of puzzles to add to the list?
Oh, I also own Mighty Mind Mighty-Mind/dp/B00000K3XI/ref=sr_1_1?ie=UTF8&qid=1384185229&sr=8-1&keywords=mighty+mind