MIT's Technology Review has an article entitled Why Heather Can Write which attributes increased writing abilities to kids who frequent sites for fan fiction.

In contrast to stories that have appeared recently discussing the deleterious effects of the internet's Instant Messaging technologies, this article focuses on what kids can learn by reading, reviewing, and writing online material. The specific context is a web site called The Daily Prophet, which is a fan fiction site (based in Sterling, VA) run by a 501(c)3 corporation that is dedicated to people who want to read about and write about Harry Potter.