If you are looking for a free Keyword Research Tool, there is one that is just launched recently.

It is a plugin that you installed into your web browser, eg Firefox. This market Keyword research tool allows you to browse Google and view the Adwords keywords of ANY Adwords advertiser!

When you do a Google search, the software automatically places a “view keywords” button below every single Adwords advertiser.
Click the “view keywords” button and really neat popup window appears that will shows you the keywords that the Adwords advertiser is bidding on, other other information, like how much they’re paying per click, etc.

Here’s the link where you can get the
=> Free Adwords Market Keyword Research Tool