Ok now this was way too kewl. I always wondered how they did some of the special effects in movies. This has some great footage and explanation of how its done.
http://www.digitalair.com/techniques/index.html
http://www.digitalair.com/techniques/index.html
The links below detail a variety of Digital Air's innovative visual effects techniques. Each page includes technical notes, an example, and a brief description of the equipment and process used to produce the example.