Adsense Ad's - Which work the best?

This is one of the most asked questions in the Google Adsense world.
Which ad's work best and which ad's are running on my website or blog.

Google has the answer, you can download the Google Adsense Preview Tool.
This cool piece of software, will show you which ad's are running on your website or blog.
Their are a few options too, i live in Spain and because my IP address is here, i get lots of Adsense Ad's that are Spanish and based in Spain and even my area. This will obviously not show which Ad's are running in lets say, San Francisco, California.
This is quite a draw back for me, but after a using the Choose Options menu, it is possible to see Ad's from different locations around the world.

Download the Preview Tool Here. You must use Microsoft Internet Explorer for this tool to work.

And whatever you do, don't click on your own ad's, thats just plain silly!