Barbie Girls is a spot for girls to connect with each other online. Girls can style their own avatar, decorate their virtual room and earn "B Bucks" for playing various games. Barbie Girls also allows you to walk around and meet other members. The site can be a bit slow to load, but the different areas are colorful and imaginative. The games are standard fare. This site will most appeal to your girly-girls who enjoy talk of makeovers and boys.
Recommended Ages: 8-15
Cost: Free for basic membership, $5.99/month for VIP (multi-month discounts available)
Other: Girls who own Barbie Girls devices can unlock special features like clothes and a "Best Friend" chat.
Bella Sara isn't the same type of virtual world as others on this list and it isn't only designed for girls. But, since it has a definite girl appeal and a virtual world appeal, I'm including it here as another option. To unlock Bella Sara, you purchase collector cards (similar to other card collecting games) that allow you to adopt your own horses and purchase other fun virtual items. Girls can groom, feed, and train their horses, and play cool games. Bella Sara is a nice alternative to girls who are less interested in fashion and makeup.
Recommended Ages: 5-12
Cost: Unlock horses with collector cards that cost a couple of dollars per pack.
Other: Bella Sara has a whole line of products including books, video games and craft kits.