For years I pretty much just hung out on gun forums, with the occasional foray to a motorcycle forum or something like that for a quick question.
Months back I joined a couple of knife forums, and more recently a guitar forum. It's funny how the threads on all of them could be interchanged simply by substituting the names and brands and types of widgets.
Some thread title examples:
1. Do I have a (gun/knife/guitar) addiction? (Usually the thread is an excuse to brag about how many guns or knives or guitars the poster has)
2. I can't decide between a (Springfield Trophy Match and Kimber Gold Match/Beltrame swinguard or AGA Campolin picklock/Fender Telecaster or Les Paul Epiphone). Invariably, one poster will advise the OP to buy (Ed Brown/Pat Havlin/Ibanez).
3. Is the quality of (Colt/AB/Gibson) going downhill? Again, there will be a poster advising to buy (Ed Brown/Pat Havlin/Ibanez).
4. Which (gun/knife/guitar) for (daily carry/work/weddings)? Expect advice to buy (Ed Brown/Pat Havlin/Ibanez).
I believe it's possible to have one forum that covers a couple of hundred different niches. Just click a radio button for your hobby when you log on, and each thread will be adjusted to reflect the hobby you chose, whether it's guns or knives or guitars or motorcycles or computers or cookware.
APS is an exception. I don't think there's anything as eclectic anywhere else.