Literature: https://www.gnooks.com/discussion/
Movies: https://www.gnovies.com/discussion/
There must be around 100k forums in there. It was a pretty crowded place back then with a lot of cool people. Moderation was a full time job though. And very stressful.
As ads became less and less of a way to make an income online, at some point it was just too much work to justify continuing it. So I closed them.
I still fantasize about reopening them one day. Maybe with paid memberships. That would allow to keep the work under control (because fewer people sign up) and to pay someone to do the moderation.
PS: Man, I haven't looked at the discussion boards for years. Now that I do, I notice how archaic it is to not have suggestions in the search bar. You have to type the exact author name to get to the right board. One moment, let me implement typeaheads ... I'll be right back ... done!
Most 2000s-era communities have been swallowed by the reddit leviathan and are now made up of similarly low-quality, validation seeking type of discourse.
https://sqwok.im/p/ReSGugPjqF4lhw - "Any recent interesting books, you've been reading?"
It's a search engine specifically for forums and discussion content (think message boards, Discords, Twitter, and ofc Reddit). If you try some literature/cinema queries, I think you'll end up with something interesting.
I tried "favorite books all time" and found a few literature forums: booktalk.org, forums.onlinebookclub.org, bookcrossing.com/forum, kboards.com, worldliteratureforum.com, proz.com/forum/literature_poetry-22.html, forum.thegradcafe.com/forum/43-literature-and-rhetoric-and-composition/