The question is how can you increase your Adsense revenue without increasing the number of web visitors? The key to earning an income with Google Adsense is to have your ads match the rest of the site, making them look like part of your content. Your focus is to avoid having the Adsense blocks look like blatant advertisements. The following are six ways that you can do this and increase your revenue at the same time: 1) Find the right place- Most website visitors read content that is in the middle of a webpage. As a result, the best place to put your Adsense block is in the top part of the page, at the beginning of your web content. You want to weave the Google Ads into your web content to give the appearance that they are extra links which expand on the information of the page. 2) Use the Large Rectangle-With Google Adsense, you have the option of picking different ad formats. Most of the time people opt to use the Leaderboard (728x90) or Wide Skyscraper (160x600) style ads. Unfortunately, this is the wrong choice, because both look like blatant advertisements. Instead smart webmasters have found that using the Large Rectangle (336x280) yields the best amount of click-thrus. Read the other 4 points here : http://mumbaikar.org/adsense/6-easy-ways-to-increase-your-adsense-revenue.asp
"Wide Skyscraper (160x600) style ads" Actually from a recent study by me, I've found that the 160pxX600px ad banner will really hurt for earning if you keep the banner there for longer than 3 months. A 200pxby200px is walk the other ad size any day of the week.
It all really comes done to traffic and content, the more of each the better the earnings will be from google