Online game Moshi Monsters has 50m registered users

"Moshi Monsters, the UK based social network aimed at kids that takes many a visual cue from Nintendo's Pokemon series, has hit a landmark 50 million registered users. The figure means that now 1 in 2 UK children aged between 6-12 own a Moshi Monster account, with 1 new sign up every second from over 150 nations across the globe.
Letting kids interact and play online in safe, colourful environment, Moshi Monsters lets kids care and nurture for their own little online monster pet."

Source:  Tech Digest, 6th June 2011