www.buildabearvile.com is really cool and its free
Stardoll is the worlds largest online community for girls.
yes there are worlds for girls binweevils.com scplus.com girlsense.com webkinz.co.uk bellasara.com and tjhats all of em
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.
at runescape.com
there issmallworldsmovie star planethowseweeworld
wizard 101
bella sara,woozworld,girlsense,pixie hollow,barbie girls,club penguin
You can't play it online for free but you can share home made worlds but you need wi-fi for it.
imvu.com smeet.com secondlife.com rocketon.com
super secret
Neopets
What do you mean? If you're looking for free online worlds to play, here are a few: runescape.com dragonfable.com adventurequest.com chimpoo.com If you want to know how to make a free online world, sorry. I don't know how. :(