I actually love the Keyword Planner. I've found the whole process far more streamlined than the past segmented processes with the Tool & Estimator. I posted a how-to on my blog about how to use it most effectively. http://www.baeronmarketing.com/blog/how-to-get-the-most-out-of-googles-keyword-planner
Google AdWords Keyword Tool This is the old keyword tool that we all know and love. You type in your keyword and it gives you the competition, search volume, and cost-per-click (CPC) for your keyword and related keywords as well.
Keyword planner is the best, but you need an aAdWords account, go ahead create one, you don't have to pay nothing.