Wordtracker is probably the most popular keyword analysis tool in use today and allows users to assess keyword traffic and keyword competition.How Wordtracker works
free version of Wordtracker finds the number of searches using a different search engine – AltaVista. Paid versions of Wordtracker allow users to choose Google, MSN, Yahoo, etc.
WordTracker. The first thing you can look at is their free trial. It’s great for getting a feel for how the system works, but I wouldn’t recommend it for any kind of serious project.
Beyond that, you can sign up on a daily, weekly, monthly or annual basis.