Wordtracker compile a database of terms that people search for. You enter some keywords, and they tell you how often people search for them, and also tell you how many competing sites use those keywords.
Wordtracker helps you find all keyword combinations that bear any relation to your business or service - many of which you might never have considered.
You'll find out how popular keywords really are, then for each major search engine, they'll show you the chances of making the top 10.
Click here to read more about WordTracker