I recommend these:
Club Penguin.com
Dizzywood.com
Fantage.com
Minimonos.com
Ourworld.com
Freerealms.com
Webbliworld.com
Woozworld.com
Planetcazmo.com
Ecobuddies.com
Dinokids.com
KidsCom.com
Franktownrocks.com
Chobots.com
Smallworlds.com
Secretbuilders.com
Mydinos.com
match
Yes, there are. Such websites as SimCountry, Cyber Nation and NationStates are good virtual world websites.
yes
imvu.comhabbohotel.comourworld.comevony.comhope they help!
There is Woozworld its awesome!
ggg.com
imvu
Maybe for your kid i would say that secretbuilders is a good virtual world!
the best website in the world for tweens is thetweenmagazine.com
The names of some good horse websites are: Horseland, ClubPonyPals, Howrse, Horse Isle.
I would say that http://www.smallworlds.com I one of the best virtual websites. It has won numerous awards for example Adobe 2009, which was recent.
there is zwinkiecuties stardoll moshimonsters myminiworld virtualfamilykingdom or doms