I'm friends (IRL) with MechaKoopa and he linked me here. Me and a bunch of Gamefaqs guys on the SSBB board made our own forum a few years ago (just a few months after the gamefaqs SSBB board even came into existence). Anyway, it was an invisionfree forum and was very active for a good 2 years or so. I was one of the admins there and did a lot of the technical stuff.
Anyway, I guess my point is that I'm pretty familiar with some good ideas for new forums. One thing I'd like to suggest is a "Welcome Forum" for all the new members. I kind of gave my introduction in this forum since I had no other place to put it.
Another thing that you might want to consider is making ranks for how much people post. We had ranks and the name of your rank increased as your posted more and you got a new avatar at each level. Also when you'd reach certain ranks a secret board would open up to you that you could then post in. The secret boards weren't visible prior to reaching that level. The good things about ranks is that it makes the board very active since people are competing to get posts and unlock the secret boards. The bad thing is that it creates a lot of spam...so it's up to you guys.
I board that we really liked in our old forum was the "$%#^%$&%!" board where you would vent your frustration. Usually gamefaqs mods related frustration lol.
Anyway I have plenty of other ideas I'll post about later if you guys like any of these. Nice to meet you all.