I hope to chip away at the draft table of contents with an article or two a week until it's done. My first new code for the site is a basic Processing library for manipulating GPS data from GPX files. There are bound to be bugs and niggles, if you have a GPX file you could try it out with I'd be really grateful.
Here's an example app showing a friend's recent travels. Excuse the file name, as you can see the data is quite noisy and it needs some cleaning up. Also note that the Arcball class isn't quite working right (it needs fixing up for newer Processing versions), but it helps give you an idea of what's going on.