As a follow up to the article I wrote about my experimenting with different ad systems for facebook applications, I have had several requests from developers who want to get targeted ads to show up on their facebook applications.

To allow adsense to be targeted on facebook applications, you first have to realize that adsense code cannot be added directly on a facebook page, due to javascript limitations.

The only way to get around this is to pull adsense ads via an iFrame box, where the adsense code is actually on a different page somewhere(not a facebook page). On this adsense page, you must do a few things to make sure the ads are targetted, or else google will just send random ads with no targeting.

I target the ads by putting entering meta data on the page holding the adsense code. I also name that page something specific to my sites general topic. While you probably cannot make EVERY page of your application targetted like it normally would, you can at least get targeted to the general topic of the application.

Something else you may consider is using url parameters in the end of the url for the page holding the adsense code, and use those parameters to change the overall targetting.

For example, I can use iframe src=”site.com/facebook/apartments.php?city=Raleigh&page=Reviews

I can then take these url parameters to help target the meta data so that adsense can focus its advertising better towards apartment reviews in raleigh, in this example.

Hope this sheds some light into the facebook/adsense universe for you.