A WebmasterWorld thread has discussion on an Inside AdSense tip telling people to try rotating in and out your AdSense blocks with non-ads. Google specifically recommends Related Links;
And if you're feeling especially creative, try alternating between Google ads and Google Related Links in a given space on your page. This will encourage people to look in that space for interesting dynamic content.
To be honest, I don't think, that if I would do the rotating tip, that I would use Related Links as what I rotate in. Why? Because when related links were first launched, people thought that these were ads, they confused them with an other AdSense product. By rotating out the ads with what may appear to be different ads, may not be too wise, IMO.
What I would suggest is to rotate the ads out with real free content (related links generated internally, related images, user comments, etc.). Real content that appears to be related to your content and not something that appears to be ads.
The question is then, what percentage of users to you show ads and what percentage of users do you show real content? At what point are you making the maximum amount on your ads? That is for you to test and test with your metrics.
Forum discussion at WebmasterWorld.
