The Ultimate Collection of SEO Tools

The folks from Search Engine Journal created a nice compilation with the best, and free, SEO tools around the web. All of them work as online applications so you won’t need to download anything.
An interesting feature are the comparison charts that they created for each category, like the one below:

You will find backlink analysis tools, keyword research and brainstorm tools, domain name tools, on site analysis tools and search related tools, so check it out.