what forums are out there that people actually go to, besides Lemmy?

The Android rom ones like xda forums are active.
This is definitely not what you’re looking for but college sports forums are active if you want to read the dumbest shit ever.
I’m from Louisiana so I’ll pick on my own team and link to to Tiger Droppings:
https://www.tigerdroppings.com/rant/lsu-sports/
The recipe posts are actually good. It’s basically a forum for insane people who get mad about LSU gymnastics recruiting but then post an alligator sauce picante recipe that’s better than anything you’ve ever put in your mouth.
- Here’s the food/drink topic section:
  https://www.tigerdroppings.com/rant/food-and-drink/
  It’s insane (compliment) and also insane (derogatory).
  
  A jambalaya v.7.3 ratio spreadsheet exists:
  https://www.tigerdroppings.com/rant/food-and-drink/latest-fandd-board-cookbook-parts-1-and-2-plus-the-jambalaya-calculator/110548628/

Spacebattles is still alive.
Nexusmods "forums" and pages still have some social activity.
TBH it’s pretty barren. I noticed that even comment sections are drying up.
- TBH it’s pretty barren. I noticed that even comment sections are drying up.
  You mean across many websites don't you?
  I definitely see a lot of websites with a comment box that it is just a wasteland lol.
  I am sometimes like, jeez why even bother to include a comment box 🤣
  
  I assume they are just harvesting email addresses unless a very small site

https://forums.whirlpool.net.au/
- I love how Whirlpool has stuck to it's guns with regards to staying text only.
  It survived a world of phpbb, avatars, and animated GIFS and is now surviving a world of social media and "engagement". It's like Usenet with moderation and no binaries.
  Helps that it's fast as blazes too.

I know this won't interest most lemmy users, but the forums for most large american colligate sports programs are alive and well.

tildes seems pretty active
spacebattles as well
and the dwarf fortress forum, too
- The Dwarf Fortress forum is most likely full of big bearded dwarves. Also the Elder Scrolls lore community is my magical hangout, Warhammer too.

The EndeavourOS forum to give support (I use base Arch, but they're close enough), the Lutris forums, and Blenderartists. Stackoverflow and similar services, and various issue trackers, if you count those.

The only two that I ever still make use of are XDA for custom firmwares and other Android related shit. And Pokecommunity for the ROM hacking / decompilation stuff.

cs.rin.ru

Larger open-source projects tend to have forums. Here's a few off the top of my head:
https://forum.luanti.org/
https://tavern.dcss.io/
https://users.rust-lang.org/ (and https://internals.rust-lang.org/ )
https://forums.opensuse.org/
- Openstreetmap also has some forums. The main one being community.openstreetmap.org

There are so many niche forums.
Here's one I found a while ago when I was looking at repairing an old electric fan I found: Antique Fan Collector's Forum.
In the way that people would always add "reddit" to their searches, try just adding "forum".

https://budgetlightforum.com/ flashlights et cetera
so many automotive forums
https://eevblog.com/forum electronics engineering
https://www.audiosciencereview.com/forum/ audio, lots of diy
https://www.finishing.com/ - metal anodising/plating/finishing. This incredible forum has been running since before the internet, originally a BBS.
https://www.automaticwasher.org/ washing machines and dishwashers
https://elektrotanya.com/ electronics repair

Blenderartists.org for blender news, learning, and sharing of addons and stuff

Special interest forums still hold.
For me, the Royal Enfield motorbike forums are exceptionally good, and that's largely down to the admin. There's also a Series 2 Land Rover forum that has a unique collection of people with a phenomenal combined knowledge about that car.
I've hosted a few in my time - since the early 90s and Fidonet when BBSs were the thing. But things change. Facebook killed of a whole bunch way before Reddit and Lemmy just because that's where people were already, and it was easier for them to feel involved. Facebook is impossible to search, though, so the post history of a forum that was so useful has gone entirely.
It's sad, but things change. What's constant is people's desire to socialise and discuss topics they are interested in. I'm kind of curious what that will be next.

This varies a lot by individual, but I have a Newgrounds account and I post to the forums that are there too!
- I hope Newgrounds implements activity pub

Isn't Reddit or Lemmy pretty much just a structured forum?
- (early) reddit was the answer to the question "what if anyone could have their own phpbb instance without having to host it?" Then along came Lemmy asking "what if anyone could have their own reddit instance and have to host it?"
  
  lol!

Car forums are still somewhat active. There's usually one per car make or chassis. For example I use zilvia.net for S chassis stuff and miata.net for Miata stuff which are both active.

https://forum.level1techs.com/

https://bbs.archlinux.org/ btw

https://tildes.net/ is still quite active and while the interface is similar to old reddit the focus is more on discussions than sharing links.

mumsnet. 10 million active users.
- What is it
  
  It's a place where you can ask questions that need an answer along the lines of "all men are bastards and need to be kicked to the curb immediately, can't ever change, and no woman has ever done anything wrong".
  
  pipeline to fascism
  
  TERF forum
  
  British forum for mums to share parenting tips. Different demographic to most other social media.

https://forum.language-learners.org/
Language Learner’s Forum is still quite active and pretty large community.
https://latindiscussion.org/ Latin Discussion is still pretty active
If you like Sid Meier’s Civilization then CivFantatics is really quite active very much.
There are the Woodwind.org forums of course but they aren’t as active as the others. I think that Saxophone.org is somewhat active but less so than it used to be.

People still post to lobsters
- Would be nice if they actually let people join!
  
  Would you like an invite?
- Not many though. On the FrontPage, the only post that has Kore than a few comments has 70, which is not many, by today's standards.

Shared by @Obsidian@lemmy.one on the other thread
https://aftermath.site/best-active-forums-internet-today?ueid=6310597850b065b278e2b143b21b73b5
- Over the years, forums did not really get smaller, so much as the rest of the internet just got bigger.

Usually something hyper specific. This was a few years ago but I found a very bustling community forum for appliance repair. I posted a question on how to fix my oven and got very detailed answers and technical info involving the circuit board and heating element and troubleshooting steps. Unfortunately the general consensus on there is that for a lot of appliances, the board needs replaced which may or may not be available, and if it is, costs damn near what a new appliance does. Which is obviously done on purpose to drive sales.
The other one I know is my friend will participate on one for modding Toyota Yaris cars.
Bodybuilding / fitness forums are still pretty active.
All of these tend to have subreddit or Lemmy equivalents however.

All the forums I used to go to on any regular basis are dying out or dead - NotebookReview, DSLReports, etc.
I still stop by Linus Tech Tips forum and GBATemp and Overclock.net and ServeTheHome on rare occasions.

www.knockout.chat

https://www.cloudynights.com/

SomethingAwful is still very active!
4chan is as well, but it’s been shit since 2009 (inb4 /b/ was never good)
- Remember when /b/ was good??
  
  No, because it never was.
  Kids confused it with good because it was the equivalent of running around an abandoned building throwing dog shit and broken glass at each other while spraying paint on the walls, because no adults told them not to. But when you tire of that, it's just an empty husk full of dog shit and glass.
  
  My first serious romantic partner in the mid-2000s told me “the more I browse /b/, the more I understand you” and in retrospect I don’t know how I feel about that

Tacomaworld, there is another Toyota forum but the name eludes me at this moment. Vwvortex is still around i think. My guild from a MUD i play on occasion still has a forum, as does the MUD,

I regularly visit https://vogons.org/ to talk about retro computers.

Does anyone remember Megalinks on Reddit? They started a forum after it was shut down, I was lucky enough to get invited before they closed registration. The forums are still very active and it's the best community I've experienced online. I spend as much time there as I do here.

I used to use RPG.net a lot. They have pretty strict moderation, which keeps the place from turning into some kinds of shit holes. But you also can't tell someone they're a fool, or all Republicans are traitors. Takes some getting used to, but is probably worth it.

It seems that this might be useful to add to this pile of information:
https://meta.discourse.org/t/federation-support-for-discourse/90921

I only have a Spanish one in my sight (it is like a reborn, I haven't even signed in yet, I had an account for the previous website) called foros dz.
I also have some other Spanish forums bookmarked, gaming related but I think they are just dead.

If you're into headphones and related encoutrement, head-fi.org is still thriving.

I go to mentalhealthforum.net

Gallifrey Base, sometimes 😌🤓

Retrogametalk and segaxtreme

Gbatemp is one.

cs rin.ru and ltt foums

OpenStreetMap Community Forum

Techlore forums and privacy guide

There are a few cannabis related ones, though activity is here or there on one or two. UK420, THCTalk, ICMag, GrowCity, etc.

There are some good Matrix community, on matrix.org as well as individually run homeservers (federated).
- matrix isn't a forum. it's a chat.
  
  Incorrect. Technically Matrix is a protocol, and a forum client can be made. You already have some PoC social media ones. It just so happens that most well known clients at this time and for instant messaging. But it can be much more.
- is there a matrix client for Android? last I checked there was like, one, and it wasn't very good. whereas there's like 14 different Lemmy apps, many of which are fabulous.
  
  FluffyChat is pretty good these days https://matrix.org/ecosystem/clients/
  
  I am not a big fan pf matrix but I think SchlidiChat was the one I used most successfully on android.
  From what I have seen a main issue with Matrix is that the protocol can be implemented in bits and pieces. Which is perfectly fair but it leads to an inconsistent user experience. The default web clients you first use to try it out will be using strong encryption settings by default but then a lot of the mobile or native desktop clients don't support encryption. So it's difficult to get going finding cross platform apps that have all the desired functionality consistently between them.
  In terms of the apps, I don't think comparing matrix to lemmy is exactly fair for this reason.
  
  Element X is quite good now (note the X, not the classic 'Element'). Fluffychat's good too but missing some features.

The Gear Page is very active as are sister sites like strat forums, my les paul etc
Talk photography
Fred Miranda photography forums
Av forums
Watchuseek
What HiFi
I used to live on the winamp forums, but I haven't for a long time and it's pretty dead now.