i like social media sites for promotion and google webmaster, analytic, keywords tool for web sites optimization.
My favorite SEO tools depend upon the functioning. For keyword analysis: Google Adword External, Market Samurai For competitor analysis: SEOMOZ For competitors links : Majestic & opensiteexplorer & SEO Spyglass
See, if you have asked the question is perfectly then every one will answer perfectly. but here every one playing. because your question is not perfect.
Article writing and blogging. JAparri http://www.TheAlphaOmegaSolution.com http://www.facebook.com/AOMarketingSolutions
forum posting, blog commenting, social bookmarking. scrapebox, market samurai, traffic travis. My mind.
For me properties and article marketing are the best SEO tools. Unique content and the links will be forever (mostly)
I have also one the most important tool this is a free online back-link checker tool helps to know about the quality inbound links of your website, This tool show you results of backlinks and its totally free for webmasters