I think this depends on the nature of your service / product. I have some good results for one of site thou..
Sorry, not possible to share here.. However, I have tried the following method with some success. For a service / product provider, one has a free tool for reference (such as a calculator for some purposes). Most users will exit this page after the usage of this tool. Therefore, place some adsense codes here. You can get good amount of clicks since the users already have a mindset of 'leaving' your site. I hope its clear