The Google Adsense Search is a much overlooked feature of the Adsense program.

When you register at the the Adsense program, you can choose to serve content bases ads, but also you can select to join Adsense Search.

What Adsense search does is that it gives you the option to place a "Google Search" field on your website, similar to the one below. You can define the look of the search field from within your publisher center, and choose where to display the Google logo, submit button, colours etc.

It is possible for you to "brand" your search result page, by defining the colours used, and even include a logo (50 x 50 px).

A great feature about the Google Adsense Search fields is that you can choose to have the results displayed on a new page, and thereby keeping the visitor on your site.

You can then choose from 2 different types of search :

Google Adsense Search
Google Adsense Site Search

Google Adsense search directs your visitor to a page containing both Adsense ads and search results from Google. This is the type of search listed on the bottom of the navigation bar on this page.

The second type of search, Google Adsense Site Search, searches all recorded pages from your site that is listed in Google's database. It then shows the user a result page, containing pages from your site that matches the search criteria, as well as search relevant Adsense Ads.

You can track the performance of your search fields, by creating a tracker from your Adsense Publisher center. Any clicks made from the result pages, counts towards your Adsense income.