Since this community has five members, I thought I might as well get things started a bit, with a list of some of my favorite classic literature based fic.
Picture of Dorian Gray
Letters Signed a Fool - By Mandolin77
A series of letters from Basil to Dorian, reflecting on several important moments in the book. The author really has a very good understanding of Basil's character, and the writing reflects Oscar Wilde's style remarkably well.
Jane Eyre, the Facebook addition - By Writergal85
The story of Jane Eyre, told by facebook status updates from the characters. Silly, but great fun.
Literary Agent Hypothesis - by Skazka
A little story about Mina organizing the fragments of their adventures into a book, after the Dracula ordeal is over.
Upon What Grounds - By HL (Hele)
Emma and zombies! :) It takes the concept of Pride and Prejudice and zombies, but puts it to use without all the silliness. This story is very, very creepy. the writing style is very Austen like.
Pilgramage - by Rese
An AU of Little Women, in which Meg dies in childbirth. Mostly focuses on the relationship between Jo and Laurie. All of the author's works are excellent and worth checking out, but this is my particular favorite.
Stormy Night - By Laura Schiller
A piece about the relationship between Laurie and Professor Bhaer, after Jo is married to Bhaer. The author also has many other stories, mostly focusing on Bhaer. Although I never liked Bhaer or Jo/Bhaer before reading her works, everything she writes is so effective and believable that it's impossible not to like it.
Completing the Puzzle - Dream's Sister
A series of little moments between Jo and Laurie. My absolute favorite Little Women fic ever.
20 Different Ways to Leap Through the Minuet - Mariagoner
AU - 20 different looks at what Jo and Laurie's marriage might have been, if they'd had the chance. Another author with lots of good fics, who tends to take Little Women in interesting directions that haven't been tried by the other writers in this (rather small) fandom.
Five Things that Never Happened to Damon and Pythias - by Dhobi Ki Kutti
Five AUs about Dan and Nat (of Little Men/Jo's Boy's fame). It's mostly fairly mild slash. I can't say I ever expected to find, much less enjoy Little Women slash, but this is fantastically well written. The author nails Dan's narrative voice.