Quoted: FThe success of such destinations as Club Penguin and Webkinz has paved the way for an explosion of new sites for children. As of last month, more than 100 new virtual worlds had started up or were in development, according to Virtual Worlds Management, a trade group based in Austin, Tex.

Many sites such as Empire of Sports, Planet Cazmo and Xivio are aimed at so-called tweens, ages 8 to 12. For those who have outgrown Club Penguin but who are too young for MySpace, the sites offer a hybrid of a games site and a social network. This year, more than 12 million children nationwide under the age of 18 will visit at least one of these sites, and that number will grow to 20 million by 2011, according to the research firm eMarketer (which didn’t estimate how many children would pretend to be French single mothers).