Show AdSense to Google Search visitors in Wordpress ...

I put AdSense ads on my Wordpress plugin pages since the donation button wasn exactly raking in the dough. I inserted my AdSense code straight into these pages content. Looking through some of my stats I noticed a few of my posts got lots of hits from Google Search that would be good for ads. I didn want to show ads to my friends and normal readers so I went looking for a simple solution.

I borrowed some of the code used in this post, http://www.scratch99.com/2008/01/shylock-adsense-plugin-hack-to-avoid-adsense-smart-pricing/. One template function checks the referrer, if it returns true then you display your AdSense code in your post template, single.php in my case. This goes in your functions.php:

function scratch99_fromasearchengine(){
$ref = $_SERVER[HTTP_REFERER];
$SE = array(/search?, images.google., web.info.com, isearch., wouldel.icio.us/search, isoso.com, /search/, .yahoo.);
foreach ($SE as $source) {
if (strpos($ref,$source)!==false) return true;
}
return false;
}

and this goes in your post template where you want the ads to be displayed:

<?php if (function_exists( iscratch99_fromasearchengine)) {
if (scratch99_fromasearchengine()) { ?>
INSERT YOUR ADSENSE CODE HERE
<?php } } ?>

 Original Source:
http://geekyweekly.com/2009/show-adsense-to-google-search-visitors-in-wordpress