A List of Social bookmarking sites is ever changing. The main thing to consider when creating and updating your list is the quality of the sites. When I use to do everything manually I would only submit to places like Linkedin, Twitter, Reddit, and Stumbleupon. Now, with Bookmarking Beast http://www.bookmarkingbeast.com I get my new blog posts syndicated to not only the very best list of social bookmarking websites, but also the ones not many people know about. This has given my blog much more exposure not only with referral traffic but a big boost in the search engines, particularly Google.