If it was up to me -- which it isn't -- I'd reorganize and rearrange, putting the more popular forums at the top and relegating the others to the bottom. For example, the iPhone forums are mostly dead but get prominent placement, resulting in poor placement for almost all of the (far more popular) sections. The "Environmental Issues" forum looks to be largely dead. The "Adminsitrators" forum is dead, except for some posts that belong elsewhere. And so forth. That said, there's a limited amount one can do when 99% of the traffic appear to be the in ID forum. Generating traffic to other sections of the site would be good idea.
There are some good suggestions in the "General Site Suggestions" section and I'm sure there would be no shortage of suggestions if that area was revived.