Free SEO Tools

Google

Keyword Tool: https://adwords.google.com/select/KeywordToolExternal
Analytics: http://www.google.com/analytics/
Webmaster Tools: http://www.google.com/webmasters/
Page Speed: https://developers.google.com/pagespeed/

Ranking

Rank Checker: http://tools.seobook.com/firefox/rank-checker/

Web Browser

SEO for Firefox: http://tools.seobook.com/firefox/seo-for-firefox.html

Site Information

Alexa: http://www.alexa.com/siteinfo