As we know many sites on the Internet that provides free one way links. And of course the most profitable for us is a site that provides dofollow backlink. Among these sites are easy to do most is the website Social Bookmark, in addition to other methods that apply to the Social Media, RSS feeds and Article Submission.
Sites Social Bookmark was proven very effective to make our site faster indexed on Google and able to bring in traffic. Although Social Bookmark sites also have one weakness, namely many of them only support nofollow backlink.
Below is a list of sites that provide Social Bookmark dofollow backlink (Please if you have added another reference).

1. Backflip (PR 6)
2. Bibsonomy (PR 6)
3. LinkaGoGo (PR 6)
4. Mister-Wong (PR 6)
5. Spurl (PR 6)
6. Buddy Marks (PR 5)
7. MyLinkVault (PR 5)
8. SpotBack (PR 5)
9. A1 Webmarks (PR 4)
10. ClipClip (PR 4)
11. Connectedy (PR 4)
12. OYAX (PR 4)
13. MyVmarks(PR 4)
14. TeDigo (PR 4)
15. Complore (PR 3)
16. ez4u(PR 3)
17. MyPIP (PR 3)
18. Space-Ed(PR 3)
19. SyncOne (PR 3)
20. Yattle (PR 2)

If you make a fuss to submit the site one by one, there are sites that provide services to submit to the website Social Bookmark 47 at a time without visiting the site one by one. Website is socialmarker.com. With the site we just click the submit so that the work that we do far more quickly. You select you want to submit to the site anywhere. And there is also a category dofollow sites that support it, which means your link will get credit from Google. Please try you for that yet …