Here's my contribution!
HowStuffWorks explains hundreds of subjects, from car engines to lock-picking to ESP, using clear language and tons of illustrations.HowStuffWorks.com
A few months ago Allen showed me a cool article about how scientists have been able to slow down light to a virtual standstill. I told my roommate about it and he just couldn't understand how that was possible, so we looked up How Light Works on that site and found out some very interesting things. For instance, the lowest form of light is a radio wave. And everyone knows the visible colors from ROYGBIV. Infra-red is the light just before red that we can't see, and ultra-violet is the light just after violet that we can't see. I never made that connection before. Cool stuff.