Are there any sites that are like Twitter or Facebook but for younger kids?

[Moustafa]

http://www.moshimonsters.com/
when creating Moshi Monsters was to a produce a ground breaking new entertainment experience that would be fun, safe and educational for kids of all ages.

http://www.gaiaonline.com/
Online Hangout: Millions of teens spend hours a day on Gaia, exploring, chatting and just hanging out. Whether they’re posting on our forums, participating in special events, or playing our multiplayer mini-games, there’s always something fun to do.
Endless Customization: Gaia revolves around creative customization. Every member can create their own virtual character and dress it up with over five thousand items: clothes, accessories, pets, masks and just about anything else imaginable.

http://www.meez.com/
At Meez, you can create animated 3D avatars, dress up the avatars, play free games and use the avatars in virtual worlds. Use your avatar as an AIM emoticon or export it into MySpace, Facebook and other sites.

http://www.kaneva.com/
Kaneva is the first virtual entertainment world that unifies the 2D web with a 3D experience. Kaneva is the first to integrate social networking, shared media, and collaborative online communities into a modern-day, immersive 3D Virtual World

http://www.farmville.com/
Grow delicious fruits and vegetables and raise adorable animals on your very own farm

http://www.moove.com/
http://www.kaneva.com/
http://www.meez.com/

http://www.marapets.com/
http://www.panfu.com/
http://www.roblox.com/

http://www.dressupgames.com/
http://www.there.com/
http://www.clubpenguin.com/

http://www.powerpets.com/
http://www.activeworlds.com/
http://www.whyville.net/

http://www.outerworlds.com/
http://www.horseland.com/

http://www.epubbud.com/
Free Children’s eBooks for Any Reader:
Create an eBook.
Digitize a Real Book.
Upload an eBook.
Download an eBook.

http://togetherville.com/
Togetherville is a fun, safe social site where kids under 10 can play games, create art, and learn new things, with you and people you know and trust there to supervise.

http://www.famzoo.com/
Virtual accounts to track income (typically from things like allowance, household chores, odd jobs, birthday checks, change found in the sofa, lemonade stand earnings, etc.) and expenses.
Allowances that are deposited automatically and can be split between multiple accounts such as spending, savings, and charitable giving
Budgets for tracking and controlling specific expenses like clothing
Automatic Debits for recurring expenses like online gaming subscriptions and cell phone plans
Compound Interest to encourage good saving habits
Chore Checklists to pay for work that’s completed (or to deduct for work that isn’t)
Savings Goals to help plan for larger purchases
Loans to allow the purchase of big ticket items that are paid back over time

http://math.cilenia.com/en
Addition, Subtraction, Multiplication and Division, problems with numbers: 10, 20 and 100. Math Playground for elementary/primary school students. Practice your math skills. Multiplication table, print ready.

http://www.shidonni.com/
Shidonni is a virtual world for kids, based on the joy of drawing. Kids draw their virtual pets and play with them as they magically ‘come alive’.

http://www.there.com/
There is a beautiful virtual world where you can:
Create a 3D avatar
Hang out with friends
Play games
Build a home
Design and sell things.

http://www.habbo.com/
Habbo is a virtual world where you can meet and make friends.

http://www.twinity.com/
Twinity is a 3D online world that links the real with the virtual world based on realistic replicas of the world’s most vibrant metropolises in 3D.
Create the virtual you.
Build a digital home anywhere in the world.
Explore our first virtual city: Berlin.
Meet real people & go out and have fun.

http://www.secondlife.com/
From the moment you enter the World you’ll discover a vast digital continent, teeming with people, entertainment, experiences and opportunity. Once you’ve explored a bit, perhaps you’ll find a perfect parcel of land to build your house or business.
You’ll also be surrounded by the Creations of your fellow residents. Because residents retain the rights to their digital creations, they can buy, sell and trade with other residents.
The Marketplace currently supports millions of US dollars in monthly transactions. This commerce is handled with the in-world unit-of-trade, the Linden dollar, which can be converted to US dollars at several thriving online Linden Dollar exchanges.

http://www.lively.com/
Create an avatar and chat with your friends in rooms you design.
Create your own virtual space: Chat and interact with your friends in rooms you design.
Express yourself: Customize your avatar and stream personal photos and video.
Add your room to your site: Invite your friends to chat and help decorate.

http://beta.atmosphir.com/atmosphir/
Explore thousands of challenging levels filled with puzzles, combat, secrets and old-school platforming.
Play with a console-quality 3D graphics engine, right in your browser window.
Join your friends in cooperative or competitive multiplayer matches and move up the leaderboard rankings.
Customize your character and choose from hundreds of outfits, weapons and special effects.
Design your own levels in minutes with a simple but deep editor tool.

http://www.platogo.com/
Platogo is a social gaming network, and is the first platform to apply the Web 2.0 paradigms of user-generated content and strong community focus to browser-based gaming in a way that’s attractive to gamers and developers alike.

http://www.admongo.gov/
This Federal Trade Commission campaign aims to educate tweens (kids ages 8 to 12) about advertising so they can become more discerning consumers of information. The goal of the campaign is to boost advertising literacy by:
Raising awareness of advertising and marketing messages
Teaching critical thinking skills that will allow tweens to better analyze and interpret advertisements
Demonstrating the benefits of being an informed consumer

http://docrew.com/
Do Crew cartoons are buck teeth-full of fun and we want YOU to join the Crew! With your webcam, you can help build a beaver lodge, play dress up with funny outfits, raft down waterfalls, dance and sing with Tech, Doodle & Pickle, and have a blast exploring the rest of Beyond Pond. Join the Crew today! It’s free and easy!

http://www.carrotsticks.com/
CarrotSticks is an online multiplayer game that improves math skills for 1st – 5th graders as they practice and compete with peers around the world!

http://www.neok12.com/
NeoK12 features online educational videos for K-12 school kids on science, math, social studies, language and other subjects. The videos have been selected, reviewed and categorized by K-12 teachers based on national curriculum standards.

http://www.zimmertwins.ca/

http://www.shidonni.com/
Shidonni is a virtual world for kids, based on the joy of drawing. Kids draw their virtual pets and play with them as they magically ‘come alive’

[Arindam]

yes. frendster and orkut.