Tried reading some fan fiction (mostly Manga/Anime because I know the story-lines well and they make good fanfics). You’d be surprised how MUCH of it there is, and how good some of it is. I found one which completely re-told the Naruto storyline, but from the perspective of Shikamaru’s sister (she’s not in the Manga or Anime, called Shikako).
Of course, there’s also a lot of completely terrible, grammar and punctuation-free stories with terrible storylines, but you can easily pick those out from the titles (whether they use a capital letter, for example).
If you want to read them, you have to be familiar with the characters and story of something. I suggest becoming familiar with a manga (I recommend Naruto or Bleach, the One Piece fanfics are AWFUL).
The main fanfiction site is http://www.fanfiction.net . Happy reading!