EYE SCIENCE!

I love the internet.  This is a GREAT video about how your eye works, why you have a blind spot and where it is, and a few other interesting facts.  At the end of a video, he explains how to see blood vessels supplying the cells in front of your rods and cones.  It works, you can do it with him during the video.
Highly recommended, a great science/physiology mashup.