I just found this another link building strategy in the net and maybe it also help to the members:
Step 1;
Look for HIGH PR tumblr sites.
If you have scrapebox you can use it to scrape url fast or use google
using this footprint site:tumblr.com + "any keyword"
Step 2;
create another account using the keyword you are targeting as your username;
Step 3;
In the dashboard you can see in the menu bar click Untitled --> Settings and check use costume domain and put your domain i.e "domain.com" no http:// and no subfolders and hit save!
Step 4;
Using SEO quake you can determine if the post in tumblr has PR and if it has high PR then all you do is to reblog the post and it will credited to you.
just take some sec and refresh the post and then you will the get the high PR backlink to your site you will see it below.