Lots of these links are dead, but I have decided to leave them all up as a monument to days past. Now that we have AO3, it's easy to forget that the old fanfic archives were unstable and temporary. Favorite fics could disappear forever without warning. Even your own work could disappear without warning. Finding something to read was often a struggle, checking dozens of archives for updates, instead of just one source, and nothing was tagged for easy sorting. New to a fandom? Good luck tracking down its home. So here, sweet summer children, is a look back into the past. Enjoy.
And if you are new, here's where you find most fanfiction these days: Archive Of Our Own.