This is a great community, wouldn't it be fair to keep it 'focussed' on its main purpose?
I will compare it to another, non photographic, forum I post on.
My other forum is vibrant and lively. Posts get answers almost immediately. There is a huge range of knowledge. The site is divided into only 2 sections - on topic and off topic.
Now and again someone puts up a post similar to Phils idea It always gets shot down, politely. People see it as a club where they can discuss on topic but can also ask and get answers to almost any subject - things that come up are car repairs, plastering, shed building, relationship advice, politics, which breed of dog should I get, best place to buy kichenware etc etc. Its fantastic as people log on to the forum all the time, just for random chat, but it also means they are there to spot the on topic stuff and give quick answers. I have been a member for oh, 7 or 8 years. Its fantastic. Best of all, it keeps the forum alive.
Over the years I have searched for new photographic forums and found loads that tried to launch ande for failed, or that worked for a long while, then the best contributors got bored and moved on and gradually the forums get quieter and then die.
The trouble is, on any forum, there are only so many questions people can ask and after a couple of years, just like photography magazines, the same topics go around all over again. Long term people run out of stuff to ask and get bored of replying to the same questions time after time.
The other forum i attend is incredibly strong over a long time span, simply because whenever you log on, there is always some question you have never come across before and perspectives on issues that can be thought provoking and really helpful and supportive. it has a real sense of community and plenty of regulars, so amazingly people do not get 'lost in the crowd' despite the activity level being high.
It seems a very effective model for a very active forum and seems to ensure a long site life span.