I don't read all that much fanfiction, but you can toss 3 or 4 URLs my way for now.
You really should check out The Show. They deal with a lot of urban legends like "the woman in white", Hookman, Bloody Mary, a Shtriga, pagan gods and vampires.
They've also done X-Files type themes like shapeshifters (they are doing it a third time in season 4) and they did a Groundhog Day type episode in which Dean gets killed over & over (which was a lot funnier than it may sound).
I don't know if you watch any of those GhostHunters type shows, but they also did one of those in season 3 with a couple guys who were in season one. Those guys are also hysterical. They were the Hellhounds (there is a real website called hellhoundslair.com
) in season 1. Then in season 3 they showed up as the Ghostfacers. Pretty hilarious episodes. Their names are Harry Spangler and Ed Zeddmore--kind of spoofing the Ghostbusters.