Over the last couple of years I've noticed a couple things in the search space: 1. keyword tools are unreliable 2. PPC traffic can show some valuable search trends. Well here’s the point: PPC and SEO help to inform each other consistently.
Finding the proper keywords is the cornerstone of any successful SEM campaign. I imagine every PPC manager out there begins a campaign with keyword research in order to find what keywords are going to generate the desired traffic to a website.