Ok... so from this thread, its obvious we are passionate about the scene and the well being of this site. So I'm going to throw in some suggestions, that I think in some small ways has helped my wifes site.
1. I have setup User Ranks and User Titles which is similar to what you see on the left side with the Level Meter, maybe we need to revisit that here and set it up. I'll post screenshots, with this post.
User Ranks: So for example as you can see, a new member with no posts, is just a small dog and they post more the dog grows in length, being a Dachshund related site its an appropriate graphic.
User Titles: Same as above but in text form, as you can see as the individuals post and reach the target numbers they have different titles.
BTW: People dont know what target they need to hit before getting to the next level, which makes it fun and a surprise so it encourages people to post to see what the next level is.
We also have special ones for Administrators, Super Moderators and Moderators.
2. Flash Chat from TUFAT
http://www.tufat.com/s_flash_chat_chatroom.htm it was $5 to purchase and the members on my wifes site use it all the time. Its an IRC Style chat system, and you dont have to rely on any external servers. Best part for us, its a Private Chat System, so only members can access the chat, it integrates with phpBB and other popular forums.
3. Arcade system, we've got v3 Arcade which people can play all kinds of games which include classic clones like pacman, frogger etc.. and members can challenge other members.
4. CometChat: Yes although we have FlashChat, we found some users were leaving us for FaceBook so CometChat adds the same functionality as FaceBook chat bar located at the bottom of the screen.
5. Challenges / Contest: This adds another dimension and it might be harder to do on this site, but might be worth a shot. For example on some art sites that I frequent, they have monthly challenges. So for example Month of July challenge theme would be do a Space Scene, and people do their artwork around a Space Scene and people vote on them. The Winner gets to pick the theme for the next month August, and so forth.
All this stuff I mentioned above generates activity and helps keep the place alive.
We can look into doing things like that over here.
PS: I'm not trying to tell anyone how to run this site, which has been running great, I'm just making some suggestions that may help increase participation.