Social bookmarking means sharing link with each other or promoting a site that you liked. One individual can submit same link only once but you can submit deeplinks also but all only once.If you get high no.s of comments then it's sure you wmill get a tons of traffic to your website.This also won't work if your website is worthless. You won't earn a lot from this type of traffic as the users of these types of websites are very informative and they know when they click ads you will earn money so don't expect for a lot of earning from this but you can get you PR increasing heavily by submitting to these websites... So it's best for SEO. some of examples are digg,stumbleupon etc. which are the most used website for bookmarking.
Social bookmarking is a method for Internet users to store, organize, search, and manage bookmarks of web pages on the Internet with the help of metadata.