I dont know if my niche will quite fit the site yet, but I've followed a lot of animal subs ( crestedgecko, aidke, partyparrot, the twenty thousand cat subs... catsbeingcats of course a favorite ) and also a lot of botany style subs ( botany is the obvious one, houseplants, houseplantcirclejerk, savagegarden, mycology ) and then the unusual to pique interest ( unusualvideos, atbge, designdesign, barbarawalters4scale, hmmmgifs )
Special call out to /todayilearned a /awwducational for giving me fun facts to share with my co workers.
I think if there were master communities it would help appeal to a broad crowd.