These tools are fairly handy as they let you know what keywords you should be focusing on for a specific page.
http://www.w3.org/2003/12/semantic-extractor.html*Note, your site needs to be w3c compliant for this to work*
and googles adwords keyword suggestion tool.
*You need to be logged in to google adwords, but you dont have to be running a campaign*
https://adwords.google.com/select/KeywordToolExternalThe W3c one tends to give you the most relevant keyword where as the google one gives you a huge range.
