The more information you can gather when determining your most valuable keywords for SEO and SEM, the better. With IceRocket’s Blog Trend Tool, you have the ability to find out what is most popular in the blogosphere and view the trends for any keywords (comparing up to three at a time).
Google has a similar tool called Google Trends (see: Keeping Ahead of your Competition With Google Trends). However, Google’s tool focuses mainly on the search volume and news stories for keywords.
IceRocket.com now has a trend tool which allows you to see the popularity of your keywords over a period of time within the blogosphere.
At the end of this article, I give examples of how to use the two together.