SEO for Firefox is a free tool that is recommended by many involved in search engine optimisation and is a tool that is often used on a daily basis due to the helpful information it is able to provide. It is able to offer information on important factors such as Twitter activity, links and PageRank too. This tool can also identify nofollow links which is useful and time saving when trying to build and establish links for a website. Other relevant and informative information is also available from using this tool.

via seoconsult.co.uk

Good list of free SEO tools which are a good start to any SEO campaign.