Gaia Online is the fastest-growing hangout on the web. Millions of teens come to Gaia every month to play games, make friends, and participate in the world's most active online community.
To learn more: http://gaiaonline.com/
Second Life is a 3D online digital world imagined and created by its residents. Residents retain the rights to their digital creations, which they can buy, sell and trade; the Second Life economy currently supports millions of US dollars in monthly transactions.
To learn more: http://secondlife.com/
Zwinktopia is a virtual world for the millions of people who have created Zwinky avatars. Zwinktopia consists of dozens of games and activities that let users shop, chat with friends, play games,participate in events and hang out in their dorm.
To learn more: http://zwinky.com/
Habbo Hotel is a popular teen virtual world with a large international following. Founded in 2000 Habbo Hotel has expanded to 31 countries.
To learn more: http://habbohotel.com/