I think it is the school year traffic. People are beginning to get bored in math class, so they are looking for something to do in math class besides math class.
Yeah, this is the busiest time we have had to date. Just for the record, this is the first time our bandwidth actually went beyond 20GB for a single month. The site is about 2.5 years old. You can look in the old news to see when we had anniversay if you want to be precise.