A site that you can use is Fantage.com
Fantage.com is a good website for kids 8-14
OurWorld, Club Penguin, Moshi Monsters, Poptropica, Wooz World, Miniclip.com, Dizzywood and AllGirlArcade.
Allgirlarcade is very good for children 8-12. I personally think it is very good because there is a chat filter and you cannot use certain words. Before I let my lil sis on it I tried typing avocado and it didnt work. You need a parents email to complete the registration
Meez is a good website too
I get on club penguin a lot you should try it.