I would try www.neopets.com (a virtual pet website), www.miniclip.com (for games)
, or http://en.wikibooks.org/wiki/Wikijunior for the aspiring scholar.
I would also recommend sights like www.runescape.com , www.fusionfall.com and www.habbohotel.(co.uk/ whatever URL your country has, this site only applies to Americans, Australians and British).