Free downloadable Mentat training calendar for 2011

A month ago, I blogged about Ron Doerfler’s beautiful Age of Graphical Computing calendar for 2010, lamenting the fact that it’d only appeared on my radar at the end of the year. Well, I’ve been keeping an eye peeled, and Ron just released his 2011 calendar. It’s not about graphical computing, but what is perhaps an equally interesting mathematical curiosity: Techniques for doing fast mental math.