There are various free keyword tools out the on the market and many offer a free trial, but these are time bound and usually restricted in the results they give you.....in that they give you one square of the chocolate bar just to tickle your taste buds. The idea of course is that you like the bit you see and are tempted enough to sign up for the package, usually as a monthly ongoing subscription.
However, there is no 100%, or even 95%, evidence or guarantees about the results they produce - they are merely projected figures based on current data from the search engines such as Google, but they are popular.
Free Google Keyword Tools
Google has it's own free keyword tool Keyword Tool External which enables you to research your keywords and analyse their potential.
Google has another free keyword tool Search-based Keyword Tool which enables you to generate keywords which are specific and highly relevant to your website.
If you are considering using Adwords you can also try Google's Traffic Estimator keyword tool.
Keyword Tools
Free trials for keyword tools leading to paid subscriptions include SEO Digger, Wordtracker, Keyword Discovery, and Keyword Spy.
There may be more free trials but these seem to be the most talked about keyword tracking tools on the web.
