In my forums, i don't want big irritating ads in the size you recommend - does anyone? And does it work in a forum, is there anyone out there who has got large square ads in a forum that one could get a peek at?
I have found that placing a textlink ad just below the menu in top has given me almost as much income as the leaderboard, the leaderboard has earlier been the biggest incomesource, but now since i added the textlink (729X15PX) in the "catbg.jpg" place this textlink gives me almost as much.
You can take a look at it here
http://www.varmepumpsforum.com/vpforum/index.php
The skyscraper in my left blocks column works better when i make it display on a light yellow color.
I guess the way you say one shoud make ones ads display is good as a general recommendation, but i think that changing and making notes of the income before/after changing the ad-style is a good way to maximise the income.
Since i started optimising my sites i have gotten from approx. 0.5% clickrate to approx. 1.2%.
I know that this clickrate is quite low, but being a forum "strictly" for nordic users i think it is quite good.