1. Google Analytics 2. Google Webmaster Tools 3. SEOmoz's Page Strength Tool 4. Sitening.com's SEO Analyzer 5. Mike's Marketing Tools 6. Summit Media's Spider Simulator 7. SelfSEO Page Speed Checker 8. Dead Links Checker 9. GoogleRankings.com 10. FeedBurner
These are all good tools, but keep in mind that rankings and traffic are not the only keys to success for a website. You also need quality content that converts well and keeps people on your site. Lots of marketers forget this and concentrate purely on link building.
All tools are very good but on page optimization is very big point for drive traffic to your website with ROI.