"This is Words and Buttons Online — a growing collection of interactive tutorials, guides and quizzes about things generally considered boring. Maths, algorithms, performance, and programming languages."

Explains how two people can publicly exchange information to construct a shared secret that an outsider cannot discern from intercepting their communications.

"This post is about the magic constant 0x5f3759df and an extremely neat hack, fast inverse square root, which is where the constant comes from."

Extremely obscure mathematical concept described in such a fashion that a five year old could follow the explanation. Amazing.

Relative primacy and CSS3 multiple backgrounds intersect to produce infrequently-repeating generated images combined from carefully positioned repeating layers.

Definitely coming back to this page a lot :)

Over 1000 comprehensive, clear, bite-sized youtube videos explaining educational concepts - a real delight.