My favorite SEO tool is the Google keyword tool as it not only tells me how many people search for my chosen keywords but offers many other long tail keyword suggestions based on the keywords I've already chosen. More than once, I've found a really good paying niche keyword just by using this tool. My other favorite SEO tool are well written, keyword rich articles. Well written content is the best thing you can have for high rankings in Google. And, it serves another purpose to keep your blog readers happy. What's your favorite SEO tool?