I am using many tools while i am doing SEO. All are very useful for me and all are my favorites.
Make sure you are up to date with what is relevant and works. Old tactics are not relevant now. Mobile Whiteboards
My favorite
download healper fast dial Google toolbar Robo form
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Thought I’d add to my answer. Wrote an article for Search Engine Watch on just this subject listing 78 of my favorites. :)
http://searchenginewatch.com/article/2156235/78-Resources-For-Every-Internet-Marketers-Toolkit
Dave Davies is the CEO of Beanstalk SEO Services, a firm offering SEO, consulting, training and ethical link building.