It seams like there are tons of keyword research tools out there. I am just curious on where all these tools get there data? It's obvious that big buys such as google have their own database.
I would assume they get them from various sites like google, alexa etc. I might be wrong tho - I usually just use google analytics over these keyword tools tho.
I use google Adwords. I do believe that all the tools gather the information from all the search engines .