Neilsen's "Blogpulse" is a helpful research tool. Go to http://www.blogpulse.com/. Then, click on "tools." You can go to "conversation tracker" and type in the name of a company or brand to see who is talking about it in the blogosphere and what they are saying. You can click on "trend search" to see the amount "buzz" that has related to the product or organization over time.

Companies seeking more in-depth analysis can use Neilsen's "BrandPulse" product -- http://nielsenbuzzmetrics.com/brandpulse