I would not know anything about FanFiction.Net if my son had not mentioned it to me recently as a place he goes to often to read Fan Fiction; I think he reads the Anime/Manga and Games section but knows about several Science Fiction and Science Fantasy authors that have areas (communities) on FanFiction.Net, including David Eddings.   According to a post on Compete.com's blog:

"….Founded in 1988 by computer programmer Xing Li this website allows users to post their fiction on a myriad of topics ranging from anime to movies and if that’s not enough, “Misc.” It’s not hard to see why people spend so much time on this website, once you read one post about the highly anticipated Edward Scissorhands II (Johnny Depp declined comment) you will be hooked. When I say hooked, I mean it: The average user spends over seven and a half hours on this website a month and logs in more than 34 times. "

At any rate, it turns out Compete.com just released information that shows FanFiction.Net does generate some of the longest dwell times (time spent per visit) of any Social Media site - Fact or FanFiction.net? More Time Spent Than Social Networks

"…FanFiction.net has the fourth highest average time spent per user. That’s right, they beat out Facebook, MySpace, Google, Yahoo! and MSN."

Interesting - it appears the only advertising on FanFiction.Net is the banner on the top of most pages.