V1 SEO have put together a list of the TOP 5 SEO Tools no professional SEO should do without.
Top 5 SEO Tools of 2011
Google+ Widget Checker – Add a Google Plus Feed Widget to your website.
Top 10 SEO Tips – Provides tips for onpage SEO
Google +1 checker – See just how many times your rivals have received a Google +1
Google+ Search - Keep up to date on what’s happening on Google+
Ping Google – Pinging page to which allows you to Ping Google with your latest blog posts
Just for Fun 
Google Rankings Checker Tool – An extraordinary system to check your rankings in Google.
Google Traffic Calculator – A new SEO tool that calculates the amount of unique visitors based on the selected keyword for the position achieved in the Google SERPS’s for that keyword.
Google Keyword Tool – See how many results Google returns for your chosen keyword.
