2,000,000 impressions per month - but hard thing to optimize a forum...

Actually some of the advertisements on my board are already sponsored ads (three places are brought to market by a professional marketing company), so basically there is some targeting and monitoring in progress.
But I just changed some of my AdSense ads: I placed one horinzontal link unit where JohnSON recommended and one horizontal link unit in every topic after the last post.
And I ordered to replace the full banner space in my board header with two rectangles in case there is no sponsored ad which can be shown. Otherwise a sponsored full banner is shown.

Next I'll take care of the inlinks and possible CPM deals for the right corner.

Thanks again so much for your help so far

 

Ok, the last 5 days I got 10 - 20 $ and an average CTR of 0,15% only by adding 3 horizontal link units.
Didn't try the rectangles so far. Do you think that they will really increase the CTR? Would seem kind of outside the content to me...

 

Now there's for the first time a rectangle in my board header - my CTR is now around 0,40% and my earnings per day seem to get over 30 - 40$. It developes...

Let's see how the next days run.