Moshi Monsters is a social networking website designed for children aged 7 to 11, though I have seen monsters tagged with ages from 5 to 68. The site designers say that fun, education and safety are the guiding themes for the website. The site combines solving puzzles, working to earn points, making purchasing decisions, caring for a pet, and making connections with others on line in a safe environment.
Children adopt their own monster pet, which they then play with, care for, and keep happy. There are six monsters to chose between:

• the Katsuma—an anime-inspired rabbit;
• the Diavlo—who blows up like a volcano when annoyed;
• the Furi—reminiscent of Oscar the Grouch on Sesame Street;
• the Zommer—a zombie doll with a missing eye;
• Luvli—the flirty heart shaped monster;
• and the cuddly little Poppet.

After customizing their monster with different color combinations, children are provided with a home for their monster.
Participants play games and puzzles to earn rox (currency that they then use to buy toys, home decor, clothes and food for their monsters). Opportunities to learn about budgeting and making decisions between different expenses are part of this process as well.
The fastest way to earn rox is by playing puzzles. Puzzles provide an educational component, challenging children to improve their spelling, arithmetic, spacial skills, logic, vocabulary, and more in entertaining ways. The puzzles get harder if the player is doing well, and get easier if the player is struggling. The child's monster acts as a cheerleader, showing great enthusiasm when a child improves their performance.
In addition to puzzles, Moshi Monsters has games. One example is earning rox by serving ice cream cones to impatient monsters. This improves mouse control and speed. It also communicates to youngsters that they must work to earn money before they can spend. It may help some youngsters gain empathy for overworked food service personnel.
Monsters get sad if they aren't visited frequently enough, and get sick and hungry if they aren't fed. Monsters do not die, however, unlike some other virtual pet games. Sick and sad monsters can be restored to health with food, tickling, shopping, and doing well on puzzles.
Players can meet other players at the forum, or on the street in Monstro City. They can go to see the other players' monster homes and admire the often humorous items they have bought with rox to decorate their homes.
A lot of thought has been given to safety. Parents must give approval before a child can join. The site does not collect personal information about users, photographs cannot be posted on the site, notes to friends on their pin boards cannot include phone numbers, email or street addresses. There are automatic filters to prevent inappropriate posts to personal pin boards and forums. Unkind posts do get through sometimes, and when this happens the recipient can report the post or even block the poster. Bullying or abuse of the rules can result in the site owners banning a child from the site.
There are no ads from outside companies on the website, and basic adoption of a monster and use of the site is free. However, there are frequent reminders that the paid level provides access to many interesting opportunities. Parents may find themselves being pestered to upgrade their child's access to the website to member access, at the cost (as of late April 2010) of $6 a month, or $30 per half year, or $50 per year.
There are quite a number of grownups who play Moshi Monsters—grandparents, parents, teachers, even one or two library students and librarians. The monsters are adorable, the puzzles can be challenging, and it is interesting to see how other players have decorated their monster's homes.
Home page:
http://www.moshimonsters.com/
Information for parents:
http://www.moshimonsters.com/parents
Cost of membership: http://www.moshimonsters.com/membership/pricing
Tour of Moshi Monsters (2 minute introductory video):
http://www.youtube.com/watch?v=TKdAmD_C1p4
Survey of children's online community sites:
http://www.nytimes.com/2007/12/31/business/31virtual.html
Reviews:
http://www.gamezebo.com/online-games/moshi-monsters/review
http://prigg.thisislondon.co.uk/2009/04/a-monster-exhibition.html
Here is a video of the game in which the work serves ice cream to earn rox: http://www.youtube.com/user/moshimonsters#p/u/5/7ZRuHUEjSaE