Once SEOquake is installed in your browser you will be able to see the page rank data of all the sites appearing in your Google Search results.

The string to use is

site: tumblr.com "like this"

This is going to return the results of all the pages on tumblr where people have liked the page. This is how you get the keyword backlink from the page.

To speed things up, set your google results for to show you 100 results per page.

On google in the top right there's a thing like a wheel. You can make any changes in there. (I wouldn't leave it like that as it's longer to run a search)

With the results pulled up, there will be a toolbar within the search results for the SEOquake plugin.

You'll see PR with an arrow. The arrow gives you a drop down menu when you click it. Sort results with

Sort ==> Z - A

This will give you the pages with the highest page rank first.