Google has launched a new tool called the Search-Based Keyword Tool which lets you know which keywords your customers are searching for and which you should advertise with based on your site's content. From an interview with Barry and Google at Search Engine Land, the goal of this tool is to "give advertisers a look at keywords that they are currently not advertising for that might bring in a positive ROI."
A screenshot of the tool is here:
Looks pretty impressive -- a lot of good information is provided. Now is this tool linked from any existing Google property or only a bunch of blog posts?
Also, it seems that Google has also updated the Google AdWords Keyword Tool. One member notices that the October 2008 number for searches has been updated. Perhaps this is related (or not) to the launch of the new tool.