Ta da, data

So what comes in the form of a forum? It is one thing to know that the most successful electronic message boards focus on internet marketing, commercial website design and domain name trading. On the latest shiny new gadgets. For PC hardware enthusiasts.

I happened upon Warrior Forum and followed their discussions at various times. I'm not engaged in internet marketing so I've never thought to join.
Passive involvement in Digital Point is also possible.

I must have been in those newsgroups from the telnet days but I've wiped those from my memory. I started on DC Message Boards and from there was asked to join or found out about Deadpan Fury and Moorgus Maximus. Razoropolis and Incandescent were to follow.
At the time it seemed good to hang out with people who knew the same references. The proliferation of similar vehicles is testament to that.

Is it a world that is inward-looking? Well, there's bound to be forums on relational databases and blogs on SQL
Nairaland and India-Forums speak to the need for an e-equivalent of shared experience, one that has the dark continent and the sub-continent covered

Android Forums speaks to the rise of the mobile phone but also the popularity of the tablet and the consumption of larger screens still. Much to consider when formatting.

AVSforum.com is the largest discussion forum dedicated to Home Theatre, cinema, and the products used

So a combination of popularity - yer home theatre and Android applications - geek technology, national pastime/continental drift and gamers as here represented by Minecraft.
This is all very well but it does show how specific forums can get; they are defined by something even as nebulous as geographic boundaries or entertainment, they're not as open as social media or personal blogs.

If your passion is for poker (the fireplace implement not the card game you play for money) then you can find information or join a discussion in the 'topics outside what this message board is about channel' they often have. Perhaps there isn't a whole forum devoted to household pokers then it would be better to look for ones on log fire enthusiasts or fireside nostalgia; something that has a good chance of including pokers, rather than hoping that eavesdropping on Somalis might uncover an attractive wrought iron item.