Social bookmarking for SEO has multiple benefits. One of course is the increased search engine traffic from Google, Bing and Yahoo, but also a great way to expand your website's brand presence. The reason social bookmarking is critical for search engine optimization and quality links is because the sites are publicly owned, moderated, and have been around for many years. All online marketing campaigns should incorporate social bookmarking, which is why I recommend Bookmarking Beast http://www.bookmarkingbeast.com because they do all the manual work for you, and get you some really great links back to your business website.