An important thing to consider is that no keyword research tool is perfect. The worst of them return obvious keywords that can be easily guessed and are highly competitive. The best of them return hundreds or even thousands of niche keywords that only a few savvy competitors are targeting. But no matter what tools you use, there will always be non-obvious sources of thousands (or tens of thousands) of additional keywords you can use to build up your campaign.... Google recently revamped their keyword research tool and has now made it available to everyone, even non-AdWords customers. This should be one of the first places you go when setting up a new campaign or creating traffic/demand estimates. Google’s tool is excellent at identifying both broad (high traffic) and tier 2 (medium traffic) keywords. Like other free data mining tools, it falls short with the super high-profitability niche keywords. It also doesn’t return actual traffic estimates – just a graphical representation of the relative traffic that can be generated from each keyword.