Author has written 13 stories for StarTrek: The Original Series, Harry Potter, Buffy: The Vampire Slayer, StarTrek: Voyager, Sherlock Holmes, Jeeves, Hunger Games, and Star Trek: 2009.
Oh my god most of the stories here are ridiculous and awful, but I'm not taking them down because I refuse to be embarrassed by my novice writings. Well, I'm still a novice I suppose. Read them if you want to--no guarantees as to quality!
Fan fiction is becoming a lifelong hobby of mine, not so much as a writer, but as a reader and as a defender of the art form. If you also fit this category, I have some recommendations for you:
Henry Jenkins's blog "Confessions of an Aca-fan" which delves into many aspects of fan culture, including fan fiction
and also his books, especially "Textual Poachers."
Constance Penley's book "NASA/Trek" which explores the history and psychology behind slash fan fiction, especially the Kirk/Spock phenomenon
The Organization for Transformative Works, which advocates for the legality of fan fiction, among other things (scholarly essays about fan fiction and other transformative works, an open archive, a wiki history of fan fiction)
And check out Free Culture and Creative Commons...also public domain and copyright law if you've the inclination.