Social Bookmarkshere and many other times we talked about the importance that they have in the phase of
backlinks increasing. Casually, I came upon this long list of sites (all Social Bookmark), in which is specified in the PR and if they are DoFollow or No Follow of each one: LIST
DirectoryRoll is sharing this social bookmarking list with webmasters and social media enthusiasts. We have 394 social bookmarking/networking sites in our list.
Obviously it is difficult to post an article on all these sites, and in a short time, but a bit 'a day you can always try.
See also, Social Bookmark Submitter, software reviews - social bookmarking tools