1. Go here to download the program http://tumblone.wordpress.com/
2. Check the video in there to see how it works
3. Find tumblr blogs by searching on google "keyword tumblr" (keyword can be anything you want - cats, mountains, nudes, faces, fighters, lego etc.)
4. pick up from the search the blogs that start with "keyword".tumblr.com not the ones that are like tumblr.com/"keyword"
5. do studies of what you download - otherwise you are just wasting hdd space