Moshi Monsters seems to have replaced Club Penguin as *the* children's MMO (and when I saw that Club Penguin had increased their monthly membership to $7.95 a month - a $2 increase - it increased my suspicions that they are losing members to the quirky British monster site). My daughter and son are playing it. They both have accounts.
There are many different activities on www.moshimonsters.com to do. My girl entered a "create a collection" contest. The object was to make a group of collectibles that your online character could have in their room. She wrote about what she thought the newest collection could be and she got a "favourite commenter" prize, which gave her a free slushie for her monster to drink. She also received honourable mention in another contest in which people had to create a backstory for two characters called Dr. StrangeGlove and ElderFurry.
This was what she wrote for the collection contest:
My collection idea is Battie. I'd be ust like the famous famous fashion doll Barbie exept [sic] she would have wings and fangs. Each Battie would wear a different outfit so you could make a whole bunch!
Both of my kids like the idea of winning in-game merchandice by entering contests. I hear they want my help to tape themselves doing Moshi impersonations. Guess I know what I'll be up to in the next few days!