If you are looking for something fun and educational to do with yourself this summer, you should consider the Math Circle Teacher Training Summer Institute. It is run by Bob and Ellen Kaplan (founders of the Boston area math circles, and authors of Out of the Labyrinth: Setting Mathematics Free, along with Amanda Serenevy (founder of Riverbend Community Math Center.)
You will learn about how children can learn math through exploring open-ended problems, playing, and asking questions. There are basically two components. You get to participate in a math circle, working on some challenging, fun, unfamiliar math, and you also get to formulate a math circle and try it out with real-live kids. During down time you can tour the impressive campus, walk/swim, or if you are not mathed out, there are books and puzzles and origami stuff galore JUST LYING AROUND. People also tend to get together in the evenings (and long into the night) to keep working on the unresolved math from the day's activities. Notre Dame's cafeteria feels like Hogwarts and the food is actually quite good. And VERY cool and smart people attend this thing. This is where I met some of my favorite math-enthusiast buddies: Ben, Alex, Jesse, and Sue. This is also where I got the idea for the Delving Deeper article I wrote for Mathematics Teacher that was published in December.
It takes place at the University of Notre Dame and is only one week long : arrive Sunday, July 8 and depart Saturday, July 14. It is a good deal at $850, which covers both tuition and room and board. Learning about the Math Circle approach will make you a better teacher, mathematician, parent, and human being. But if you don't believe me and want to find out if it aligns with your goals, your best bet is to read Out of the Labyrinth and see what it is all about. I hope you decide to go, and you love it as much as I did.