Keyword Tools
Keywords play an important role for most webmasters. Researching keywords gives you insight into the things your potential visitors are looking for, and may give you guidance around what content you should be adding to your site.
Another reason to have a good keyword research tool is to find different niches on the web that may be open to a new site that could end up with a lot of traffic right away.
Also, detailed research is critically important if you are bidding on keywords for search engine placement on Google, Yahoo, MSN or others. You want to be sure to find those cheaper long tail keywords that can get you targeted traffic right away.