After spending so much time on fandom-specific sites with much better search systems (like Twisting the Hellmouth), Fanfiction.net’s search system feels really constricting.
As such, I’ve started to hack together a little userscript to make up for that. As of this writing, it hides slash and stories which involve a list of fandoms I’m not interested in. (So I can formulate searches like “All Harry Potter crossovers except series X, Y, and Z”)
You can find it (and
instructions for customizing it screenshots) over on GreasyFork.
UPDATE: No instructions necessary anymore. It now has a nice configuration GUI.
UPDATE 2: And I now also have another little script for setting custom default values for Fanfiction.net’s own limited result filters system.