Basically, you install this free software as a firefox plugin, and when you perform a Google search on any keyword, it places a “view keywords” button directly below any Adwords advertiser’s listing.
If you click the “view keywords” button, you can see the keywords AND what the Adwords advertiser is bidding on! Plus, a bunch of other very cool stats.
While the software is free, there is an upsell with a potentially very lucrative and very clever marketing technique.
Make sure you go there right away, because I don’t know how long this application will be free.