I've just started doing a few small campaigns for my company, and just using the keyword tool to look at search traffic and average CPC for keywords can give you a little insight on how you can market your product/services (though I also realize those numbers technically only indicate what people who use Google like to search for... correlation is not causation :)
Adwords is a very powerful tool. I've been running PPC campaigns for years (I'm also Adwords certified by Google) and I'm always learning about new ways to do things with them. From market research and priming forum pumps to spinning bad press, they're a force to be reckoned with in the hands of an experienced user.
If this practice becomes mainstream, we are-- all of us-- fucked.