A long time ago, I wrote an article on The Daily Click ( https://www.create-games.com/article.asp?id=1898 ), that was basically just a long list of useful formulae. It turns out that some people are actually still reading that article, even though it was written back in 2008 and much of the information contained within is now quite outdated (plus all the image links are broken).
So, I thought I'd write an updated version, that would also offer a little explanation of the underlying maths alongside each formula - and well, one thing led to another, and now five thousand words later...
Here it is: http://www.klikology.lovestoblog.com
Anyway, I hope someone finds it useful!