From Fanlore

Finder Communities are journal communities to assist fans who are usually searching for a specific fanwork they have seen previously but don't remember all the details of (or otherwise can't find themselves). They rose to popularity on Livejournal; there are also some Tumblr blogs that focus on fic finding.

Finder communities include fic finding communities (searches for a specific fanfic), other fanwork finding communities (e.g. vid_finders), rec request communities (searches for recs of a fandom, a character, a pairing, or other themes), and those communities that do both.

Communities