woozworld and woogiworld are kid safe websites i played them when i was lil (2 years ago LOL)
and try some facebook games they are really fun :)
Stardoll and zwinkie :D
My daughter loves Moshi Monsters.
Hmmm... neopets is great :D I loved it so much. Also, Pet Society on facebook ;D
My two faves!
Try Toontown or Pirates of the Caribbean online.
I would say habbo but thats for over 13's
Neopets is your best bet, i played this when i was that age it is quite enjoyable and has loads of games to play on