I found this link that was posted by a friend on Facebook this morning. It's a pictorial description of an algorithm for computing the multiplication of two-digit numbers. I haven't had time yet to think about it, but so far as I can see now it's useful only for computing the product of numbers with one or two digits. Still, it's pretty cool.
In 2011 I had a calendar in my office on mental math algorithms called Lightning Calculation, which I believe I also mentioned in an earlier post. Check this out if you wish to train your brain in the powers of mental computation!