callivert - 1:24 am on Aug 26, 2007 (gmt 0)
First, if someone posts a link to you from their blog, it's not no-followed, and it's not an artificial link. That's different from links in the comments section, which are worth less.
Social bookmarking sites won't help you much if it's only you bookmarking your own stuff. But if it gets noticed and picked up by others, it can benefit you through links and traffic. The big advantage of social bookmarking comes if your site starts snowballing, with more and more people bookmarking it.