One of these tools is an Add On to FireFox, called PPC Web Spy. This tool show lots of useful information when you search Google.

As soon as you see the Google search results, every AdWords Ad will have a button under it. Clicking this button will show you keywords that used to activate this Ad, along with some more details such as Clicks per day, Average and Max Cost Per Click, Position and more.

You will also be able to see the destination URL of the landing page. This is the page you get to when you click on the Ad. This is useful if you want to see a landing page of an Ad and you don’t want to click the Ad, such as the ones that show up on your site as part of AdSense.

The PPC Web Spy is free to use, although it has Silver, Gold and Platinum versions, in addition to the free Standard version.

I hope you’ll find this tool as useful as I did.