General
What's Next?
Kent District Library (Michigan) offers this site for readers to find information concerning adult fiction in series (two or more books linked by character, setting, etc.). Search by author, title or series to get the proper sequence of titles.

What's Next? Teen Series and Sequels
The Bettendorf Public Library (Iowa) has created this site with a long list of books in series that have high appeal for teen readers, including fantasy books in series. Search by author or series name.

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Fan Fiction
The Derbyshire Writer's Guild
Fiction inspired by Jane Austen novels from the site Austen.com. Writings are divided into two sections: Epilogue Alley includes stories that are true to the historical settings of Austen's books; Fantasia Gallery includes fan writings set in different time periods or containing elements of fantasy.

FanFiction.net
A large site collecting fan writing in a variety of genres. Registered users may submit writing and post reviews.

Fiction Alley
A collection of Harry Potter related resources, including fan fiction inspired by the novels, book discussions, fan art and a Harry Potter wiki. Browse by character, relationship, genre and more.

Harry Potter Fan Fiction
A searchable collection of fiction based on the Harry Potter series. You may search and browse by author, genre or "popular pairings" of characters from the books.

Stories of Arda
Fan fiction based on Tolkien's Lord of the Rings books. You may become a member of the site to submit your own writing, or to keep track of a favorite author or story.