"Tag as" for communities (or instances?)

Originally, I just wanted to request tagging specific instances as NSFW. This would be helpful for posters on specific instances that do not always tag posts as NSFW but still should get caught by our NSFW preferences.

NSFW isn't always porn so the NSFW filter catches a bit much, sometimes. Excluding specific communities from the NSFW filter is an option, but that gave me yet another idea.

Expanding on this idea, it would be cool to start categorizing communities with tags, like "sports" or "news", "world news" or something arbitrary like "neat".

This would allow filtering by what kinds of content I want to view at any given time, in theory. Hell, we could even start building a master list to share for community categories in GitHub or something like that.