Google has released a new application aimed at helping AdWords advertisers to find keywords that could be effective for their campaigns but have not yet been used.The Search-based Keyword Tool analyses website content and compares this with search data to find the most relevant key terms, before going through the AdWords account in question to determine these missing keywords.Those without an AdWords account can still use the application to pinpoint keywords that could form the basis of an internet marketing campaign."Keyword targeting can sometimes feel like a guessing game," remarked Trevor Claiborne of Inside AdWords."Potential customers are performing hundreds of millions of searches on Google, most of which you don't even know about."According to a report from the Internet Advertising Bureau, UK marketers spent £981 million on paid search during the first six months of 2008, up 28 per cent compared with the same period last year.