Today, kids start wading into the social networking waters as soon as their little fingers can type, exploring digital "communities," many of them designed mainly to stoke their fascination with particular toys. New sites launch constantly, targeting an ever-younger audience.

KINDERGARTEN THROUGH EARLY SCHOOL AGE

The focus is on communal game-playing and earning points to buy virtual things, rather than socializing. There's some messaging between friends, but most sites allow young kids only to post messages using prewritten, generic phrases or words from a tightly restricted dictionary. Kids can't share personal information like a home address. Among the most popular:

Webkinz.com: Free for one year with purchase of a Webkinz or Lil'Kinz toy. Owners feed and clothe digital versions of their plush "pets" and play games to earn virtual "KinzCash." They can play video games against other kids or take quizzes designed for players 5+. They're rewarded for spending lots of time on the site, so you may need to impose time limits. Safety-wise, kids can't type messages that go beyond select phrases unless a parent approves their access to the "KinzChat PLUS" area. In that area (recommended for ages 10+), kids can only use words from the site's dictionary.

ClubPenguin.com: This hugely popular Disney-owned website charges a membership fee (about $5/month, depending on the plan you choose). Kids are represented by penguin avatars rather than by images of themselves. By playing games, they earn virtual money to clothe and accessorize their penguins and decorate their igloos. They can send other penguins a "buddy invite," visit their igloo, chat using predetermined phrases -- unless they get clearance from parents to chat freely -- and send postcards, among other things. (They can also snub each other!) Designed for kids 6-14, but open to all ages.