There is Webkinz, or Build A Bearville. Both of which you have to buy an animal to play the full game. Most of both of these online animals come with plush toys that have a code. Both start around $20.
Or for free there is, Always-IceCream.com. Which is a girls online free game. As for boys there is RideMakerz.com. Both are free. I hope this helped. If it didn't, just Google virtual worlds for boys/girls.
fantage
Zombie Dooks, Vampire Virtual
yes
Virtual worlds are NOT bad for kids! The people that interact with your child are probably bad. Some are good, some are bad, but virtual worlds are not bad! Virtual worlds are created by people that want your children, teenagers, and adults to have fun when they are bored, or at any time! Their are many virtual worlds, so don't worry about not finding the one that fits you! Good luck! :) - Sally
Try Xivio.com, its a free 3D virtual world. Safe for kids! No download too!
MoshiMonsters.com ClubPenguin.com
Club PenguinBinweevilsMoshi MonstersPanfuTinkatolli
smallworlds
secretbilders
club penguin is the best! also there is panfu
HOMEWORK.
the best are club penguin and webkinz:)