Algorithm Visualizer - Write down your algorithm to be visualized
The Data Visualisation Catalogue - Reference tool for data visualisation
Algorithmia - Algorithmia makes applications smarter, by building a community around algorithm development, where state of the art algorithms are always live and accessible to anyone.
CodeAnalogies - Visual explanations of web development topics
Grokking Algorithms - An illustrated guide for programmers & other curious people
Flourish - Powerful, beautiful, easy data visualisation