I just heard that Wordtracker is offering new subscribers unlimited 7 day access to the full version of Wordtracker for FREE! So I wanted to pass this along to you. If you aren't already using Wordtracker to aid your web sites in SEO I recommend you check it out. Keyword research is a valuable tool and Wordtracker is an invaluable resource!
They will ask for your credit card information. This is only to protect them from people abusing the system by registering several times. If you want to take advantage of their 7-day access for free, go 
Wordtracker - The Premier Keyword Research Tool for Search Engine Optimization and subscribe.