Vedic and Mental Maths Techniques

I am a mental maths junkie. All kids in our house learn these maths shortcuts even before they have been able to learn the long cuts (aka the propah way of doing things) . The latest victim is the nephew.
Finally, today, one decided that its time to get together a list of links from where to teach a child this magic of maths...(one cld have written a book and made money, but well, ahem, this is simpler, and more logical) . Almost all the techniques that i'd worked out are here now, except for a few, so hopefully, some of those will be covered in blog posts. For instance, did you know that the difference in the squares of 2 consecutive positive numbers is the sum of those numbers? i.e., 14 square - 13 square = 14 + 13? :-) Yeah, and simple things like that.

Here, then, is raw material for a book, whoever wants to write it.
http://wildaboutmath.com/2007/11/11/impress-your-friends-with-mental-math-tricks/

http://www.hinduism.co.za/vedic.htm

http://www.authorstream.com/Presentation/Santoshmehta-907-vedic-mathematics-techniques-vedicmaths-mba-cat2007-easymultiplication-squares-cubes-mathproblems-solve-quantitative-wiziq-final-education-powerpoint/ - i recommend this one.

http://listverse.com/2007/09/17/10-easy-arithmetic-tricks/

http://www.speed-maths.com/maths-techniques.php

Do u know of any similar links? For the speed maths junkie in all of us.. pls add here..