My favorite SEO tools are Open site explorer for back links and Google ad word keyword tool for Keyword Research.
Your sig says EWA pays you weekly, then why don't you just buy($97) one instead of searching for a download link?
Google adwords keyword tool is the only SEO tool I use. Other than that I use Firefox add ons for ranking check.
My favorite SEO tools includes google adward tool for keyword tracking,Google Back link Checker tool,Rank checker for checking ranks, etc.
Has to be the Google External Keyword Tool, can be quite beneficial if you know what you are doing, and it's free
I use opensiteexplorer.org to check backlinks from SEOmoz and then it is the SEO quake for pr and other important factors to watch..
My favourite SEO tool is my brain, everyone else has tools that speed up processes, but you can have more success in 10 minutes by stopping and having a little think about how to promote a site and get people interested in what you do. And the best part is that its totally free at present.... Alternatively I would say my favourite tool is Google Analytics, Webmaster tools and generally Google products.