A nice tutorial on using Big O notation to express the time and space complexity of an algorithm, using sample code in different languages.
I've been brainstorming ideas for using Neat Hobby! to create fun illustrated guides to basic computer science concepts, like complexity, graph traversal, etc. As someone who's always struggled with the abstract concepts in math, I often wish I had a fun way to visualize these. I bet a lot of people who fell into web development from art and design backgrounds feel the same.