Why Shoud You Bookmark?
Outside of boasting of finding a great post, you can use social bookmarking to drive some visitors to your site. You really never know when other people may find your post or discovery equally valuable since the Internet is really the main source of information these days.
Some people may find social bookmarking as an added effort and waste of time. In the early stages it may hold true. But eventually you will discover that efforts will not go to waste. Social bookmarking really aims to spread the word in a more formal matter rather than the usual word of mouth or off-topic link baits people practice these days.