I recently asked, are there any premade outdoor worlds suitable for testing 3D graphics? The question was put on hold:
Questions asking for resources are considered too broad here, unfortunately (because they are list-of-link generators); a good place to ask if the suggestions above aren't sufficient would be GDNet.
I agree that I'm basically asking for a list of links. I don't agree that that's a fundamentally non-worthwhile thing for this site, though it might be prone to difficulties.
In other words, there are bad (unproductive) list-of-link questions and good (productive, helpful, well suited to the community's interest and expertise) list-of-link questions.
The only prior discussion I can find on this is a Meta question from 2010: Should we allow "list of X"-questions? The consensus back then was that such questions were allowed but needed to be Community Wikis, which sounds reasonable to me.