In August I made what I thought were normal ongoing adjustments of my Adsense settings. My "wow" moment came a few weeks later when I realized that my moving average was holding steady at a previously unthinkable level. I was using the same content and there was no increase in traffic, yet Adsense was outperforming itself by 86% with very little effort on my part. How is this possible? The following two steps should take you about 15 minutes to apply to a single site (depending on how complicated your layout is).
If you've never heard of arbitrage, allow me to enlighten you. Arbitrage is the act of buying something low and selling it high, usually in a very small window of time. Internet traffic arbitrage can place a ceiling on your Adsense revenue. It's possible to purchase inexpensive traffic via sources such as Adwords or the Yahoo Publishing Network. From there, it's not difficult to convince Adsense that it should target more expensive keywords once the visitor has made it to your site.
Arbitrage is not a new concept. If you get slightly nerded out by charts and graphs like I do, I recommend the Wikipedia entry for more formulas than you can shake a stick at.
Google knows this is occurring and they do a solid job of preventing Adwords/Adsense arbitrage from happening. If it eats into your revenue stream, be assured that it's affecting Google as well. Despite their best efforts, there are enough ads that make it through the cracks and onto your content pages that there needs to be an additional filter. That's where AdsBlackList.com steps in.
AdsBlackList.com maintains a set of user-submitted "made-for-Adsense" sites and "low cost-per-click" domains. I'm a content provider so I'm only interested in the "low cost-per-click" option. If you're an advertiser you would use the "made for-Adsense" option to keep your expensive ad off of those domains.
Registration to AdsBlackList.com is free, and includes a list of 200 domains that you can download as often as you like to add to your Adsense competitive ad filter. There's a premium version as well that will allow you to download all of the domains in the list, if there's more than 200. Frankly though, since the Adsense competitive ad filter only allows 200 entries I'm not sure there's much to be gained from an upgrade.
I try to update my Adsense competitive ad filter at least once a month. The domains are updated frequently, so this is a necessary step to stay ahead of the arbitrageurs (see that, you learned a new word today).
Get Adsense Focused on Your Content
The second step to improving your revenue is just as easy. Google realizes that not every scrap of text on your site is relevant when they're determining what Adsense ad to display. For that reason they offer a way to guide Adsense towards the actual content you want them to focus on.
If you use the following snippets of code around both your content and your ads, you will find your revenues increasing.
[ Put your content and Adsense code here ]
<!-- google_ad_section_end -->
For more information on Adsense targeting, I recommend this great article by Michael Gray: How to Add Adsense Section Targeting.