Interesting primer on how the HTML5 Canvas works and a good intro to the building blocks of Canvas and it's Context.
This is a quick tutorial where you get to build "Paint" style features and a good jumping off point for building more complicated painting tools based HTML5 Canvas.
Felt like it would have been pretty simple to continue building a much more robust paint tool with canvas after finishing. Great intro lesson because it demystifies a feature that I haven't spent much time experimenting with.
Completion Time: ~20 Minutes.