In your case, I think you'd be more inclined to setup something that simply presents what you're up to, instead of allowing people to comment on it through a Forum: it's those discussions that take up your time...
Also, setting up the various forums can be time consuming, because it involves tweaking the access levels.
If you ask me, I don't think you actually wanted your forum to become busy: you changed it over so many times that it seemed like you were more interested in trying out the various programs, more than anything else.
When I look at the traffic on my site, I see a minimum of activity, and even at $5/month, I don't use more than 3% of the total bandwidth allowed, but that's fine, because the website still does what I intended it to do.
If anything, I'm thinking about adding an ad banner, to help cover the $5 per month, but I don't think it would even be worth the time and effort, especially considering how many people actually stop by the site: it'd probably be more aggravating to the users than anything else.