http://www.nopattern.com/
http://wearefree2.org/
I should point out its very small kids, btw, ankle biters
On a more serious note..
http://www.elc.co.uk/
http://www.bbc.co.uk/cbeebies/
have a look at breakfast cereal sites / micro sites.
http://www.sciencemuseum.org.uk/…
http://www.hortonmovie.com/site/…