I'd love an ActivityPub-compatible art gallery site that operates along the lines of DeviantArt, Fur Affinity, Weasyl, etc., with easy SFW/NSFW filtering, decent search/tagging (at least for the local server) and the ability to sort your own and others' posts into nice folders. I think Pixelfed can do the trick in a pinch - the technical components seem to be there - but just because you can use it for art doesn't mean people actually do.