Fanlore
Fanlore.org is a wiki about “fanworks and fan communities” hosted by the Archive of Our Own. It was founded in 2008; in 2018 it had around 45k pages, in 2023 over 65k, and keeps growing.
Its remit is much wider than Fancy's fannish or literary, "traditional" SF fandom, but with some overlap and interesting contrasts, which may be summed by the plural usage "fandoms" which is a standard way of writing and thinking there. Fanlore has certainly way more content (and editors), yet most of it would appear pointless trivia (say, on hundreds video games) to a convention fan, and on the other hand much of what is in Category:Notable here are mere formal "stubs" there, showing lack of knowledge or even interest.
Still, Fanlore excels in matters that would attract a larger number of modern, media fans: For example the history of early Star Trek fanzines, fandom, its organizations and rifts therein; fan fiction (in the modern sense, which is after all AO3's raison d'etre); or issues related to feminism, from the mid-1970s polemics on Darkover and others in The Witch and the Chameleon, described in minute detail (at the time when there was not even a single issue at Fanac.org!), to the 2010s "genderfail".
Website | 2008— |