I use Bing webmaster tools, or I have in the past, and will do so again. However, the webmaster tools as I understand them are not really there to help you find keywords. They are there to help you make sure your websites get indexed by the search engines. they help you insure that your seo is up to par, and working the way it is meant to, and to optimize your search engine rankings..
I'm not sure if that will help you at all, But I thought i would give it a shot.
There are a bunch of free, and paid keyword tools available that are worth their weight in gold. I will see if i can find a few links for you.. this has always been a good one http://www.google.com/trends
and here are a couple more that i have used.
i hope i have helped you a little bit,,Good luck