I was wondering if there are any free virtual worlds like pixie hollow and If there are what are they

There are many virtual worlds.... Depending if you are a boy or a girl, I'll put them in order:

Boys:

Disney's Pirates of the Carribean (pirates online)

Hot Wheels

Girls:

Disney Fairies's Pixie Hollow Online (fairies online)

Barbie girls

Enjoyable for both:

Fantage

Monkey Quest

Shockwave (actually a game download site, but you can play online games with other people.)

Club Penguin

I am sorry that is all the information i can give. Try to look up games on Google.