Google has launched a new site called GigaPan Time Machine. This site has high quality videos of a process over time. Each "time machine" allows you to zoom into the image and pan around as it travels forward or backward through time. There are even text annotations to explain what you are viewing. The high resolution allows some great viewing. You can even learn how to create your own Time Machine with help.
There are five Time Machines on the main page, including plant growth, and a CT Scan of a human female. Think old-school time lapse photography, but with much better visuals.
This is a great resource to use with students to explore different concepts and you can even create your own with your classes.