Google Trends is a useful tool when making tough decisions on what keywords to use in your search marketing and search engine optimization campaigns.
The tool enables users to determine, relative to one another, what term is more popular to searchers based on activity taking place in Google over the past several years. As an example, I wanted to see how popular Salesforce.com was in Google compared to several of its competitors.
Take a look at the live trend example here.
A nice feature of the tool is that it charts news stories to traffic patterns for the most popular search.
Try your own comparison using Google Trends.