I personally think adwords tool is the best freely available tool right now. Spyfu and wordtracker are other options - paid. More expensive Hitwise reports, can

I personally think adwords tool is the best freely available tool right now. Spyfu and wordtracker are other options - paid. More expensive Hitwise reports, can't beat these in terms of depth and accuracy. You should also check out google's new Search Insight at http://google.com/insights/search http://google.com/insights/search