While exploring Mind-Brain a fews days back, I came across these MRI images of the webmaster's brain. As you can see, the images were begging to be animated:

Brain Scan Viewer - Navigate brain scan via mouse and lower grey rectangle.

The applet may take a few minutes to load, depending on your connection speed. Be patient and watch the preloader. :)

Coding wise, this one was tricky; some of my adventures are documented on the processing forums. (Note: These 'adventures' will only be of interest to other p5 programmers.)