We have a parallel discussion here on why it is quiet here and with few new faces. The same happen most places. People come and go. Facebook now gather a lot of people, but most groups see a lot of activities when it is new and then it fades.
I would like to turn this on the head: I would like to know what people would like to see in a forum? What attracts your interest?
For me it is first and foremost nice to see what my friends are up to: What have you just bought? What have you just watched? Any new interests showing up? This iw what fuels my interest the most. And it is OK if there is not that many updates. It is still fun to see what's up even if it has been a while.
Next, there is always the fun of discovering new things. As I started super8database.com I have discovered so much more what's out there, but I never get tired of discovering something new.
Third there is all those tricks and detailed knowledge. When I was new this was super important, but as time flies you know more, and the two other subjects gets more important.
We are all different, and catch interest in different subjects. That's the beauty of it. So what is the most interesting to read for you?