[beeker]

Personally I have not, but my good friends who own mildly successful blogs have their ads within their content and above their sidebars, been that way for years and they say it's the best.

Also, if I remember correctly, when John Chow was just starting out with his blog and looking for ways to increase AdSense revenue he said that a 300 box within your content is the best. If you look at his site now, you'll see he still practices this even though it's not AdSense anymore.