Wordtracker
The first and most important step in any search engine positioning campaign is identifying the
keywords for which you should optimize your site. WordTracker's keyword research service is the
only one on the Internet that will provide a comprehensive and powerful database of the most
popular keywords in your industry. It has features that all other keyword research tools lack -
for instance, it will help you identify related keywords that you would otherwise never have
thought of, it differentiates between singular and plural keywords and tells you which version
is more popular, it helps you identify popular mis-spelled keywords (which generally have very
little competition) in your industry etc. It has a free trial version which will help you
identify a few keywords. However, we recommend that you subscribe to its paid service as
otherwise, you will not be able to discover quite a few keywords that can turn out to be
extremely valuable to you.