Google Webmaster tools, Bing Webmaster tools, Google News, Google Trends however, little bit thinking and self planning is best tool ever (for me)
Google Webmaster tools, Google Adwords Keyword Tool, SEONuke, Xrumer, Market Samurai, Traffic Travis, and a few others
Yeah I still use it here and there for minor things. Mostly just a secondary niche finder, I gather some data from there and dig deeper with other tools.
From there you all have share some best tool which are very good and important to use for seo, i also like keyword research tool which show us full detail's of keyword.
IMO, it's not the best anymore. One or two other tools do better than MS. You can try MS and see, I see some people are still using it happily
Google Analytics and Google Adwords are my favorite SEO tools. Google Analytics help to track the performance of your site. Google Adwords is a best keywords tool and it shows a relevant searches to our queries.
Well, I would like to add serp trends, seo doctor, serp analytics to the collection of good seo tools