A few of our favourite links
http://www.math.harvard.edu/~knill/mathmovies/index.html
http://homepage.smc.edu/nestler_andrew/SimpsonsMath.htm
http://www.tygh.co.uk/tan/tan.htm
http://www.iwbmaths.co.uk/
http://nrich.maths.org/public/index.php
http://www.mathsnet.net/
http://www.ncetm.org.uk/Default.aspx?page=22
http://www.atm.org.uk/
http://m-a.org.uk/
http://kids.niehs.nih.gov/illusion/illusions.htm