I have a good list of high PR dofollow bookmarking site from worldofdth.com/thread-97-Do-Follow-Social-Bookmarking-Sites-with-High-PR
stumpleupon, flicker, digo, orkut, squido etc. are the social bookmarking sites . for more sites just search on Google .com with keyword "Free socialBookmarking sites".
I would like to add one quality site here. it is voteblogger.com. I own the site and you can assure the quality of traffic to your site when you leave the backlink overthere.
Yes, new social bookmarking site. With 10 vote your site will get publish on the first page. Now the site have about 300-500 visitors per day and will grow up pretty qucikly. The first 10K users will get free 300 Karma credit (the way to calculate first page blog). If you have any question please feel free to ask. Santacruz
Hi Cris Mac, I promote your submit sites on the front page and add your point 300. I hope you enjoy. Santacruz
check it out this link friend here you find more important bookmarking sites:- http://www.social-bookmarking-sites-list.com/
Check this one http://www.vmoptions.com/social-networking-list.php. I think this is going to help you.