Welcome to WebmasterWorld Guest from 18.104.22.168
I find it interesting that your site has Forums that are not used on a regular basis, yet you still get many clicks.
My site is integrated with Blogs and Forums, and I was counting on the live interaction of regular visitors to get more out of this.
You just showed me that it's more about hard content and information than interaction.
Like a splash of cold water....wow.
Quite achievable with the right high profile site and good ad placement.
Certain industries also produce better CTR than others. Many AdSense publishers I know have CTR's of around 8-10% (people looking specifically to buy).