Here's an idea that has probably been weighed in on before, but:

What if this forum were to be changed to a "private" forum - so you have to create an account and login to be able to see any posts? I don't mean it in a way to cut down the number of non-contributing visitors (because it wouldn't), but so the discussions, photos and addresses posted on here are not visible to the entire world immediately via search engine results. That way anybody on the internet searching for "so-and-so's autograph" would not immediately find the address on this site as the first result and would have to actually put some effort into finding it like the rest of us. It would cut down on the amount of traffic to the site, but would also ensure that most of the people coming here would actually feel the need to sign up and help contribute.

Just my 2¢.