I'm using SEOQuake since long time. Its very useful tool. Actually this is a browser add-on. You can install this add-on from here. Let have a look short feature what this tool can do:
Find the website/blog is DoFollow or not
Simply, it cuts the link of the website if it is NoFollow.
Find Page Rank easily!
Once you installed this tool, search this one Google:
site:.com inurl:"blog" "yourkeyword"
Note: Replace yourkeyword with your keyword.
In each search result you can view page rank, alexa rank and other rankings...
What you'll get?
Imagine yourself! You can collect many DoFollow blog and comment on it or you can sell the list then make easy money!