The folks over at Wordtracker just released an e-book , The Wordtracker Keyword Research Guide as a free download.
What makes this resource a bit of a standout is the unique and useful way it is written. This is not just some step by step manual or numbered list of ‘things to do’. The folks at Wordtracker created a fictional Vegitarian Dog Food company and then asked Marketing and SEO experts to give this company some specfic advice on using Wordtracker.
Of course, I would be remiss to mention that there is a contribution from our own Bryan Eisenberg.