Aperture and Shutter speeds

http://www.labnol.org/software/tutorials/camera-shutter-speed-and-aperture-explained-in-simple-english/1715/

http://www.photonhead.com/simcam/shutteraperture.php

http://www.xs4all.nl/~wiskerke/artikelen/tap.html

http://www.ephotozine.com/article/Camera-Shutter-Speeds-explained

http://www.pbase.com/wlhuber/the_basics