Below are list of my favorite paid and free SEO tools I use on regular basis. If you are looking for a more comprehensive list, please look at Search Marketing Post after the site launches.

(Note: All links are volunteeerly and editorial. I was not paid for any of these links)

Free Tools

SEO Book – First SEO tool I used and I still use it to do quick assessment of my pages.

Paid Tools

SEOMoz – 30 day free trail. The tool is online and no downloads are required)
Link Assistant – Desktop application. Has free limited version.