Digg is the most popular social bookmarking site online. Users submit links to content they like, and other users comment on those submissions and add their own votes (called Diggs) to those links. Popular links will rise to the front page of Digg and are likely to get a lot of traffic. It’s important to understand that you may submit your own content to Digg, but if you oversubmit your own content, you will be penalized and your submissions will not be readily available to other users. User caution and submit not just your own content, but other links of interest as well.read more..
StumbleUpon is very easy to use if you download the StumbleUpon toolbar when you register. When you find a webpage you like, simply click on the “thumbs up” icon on the StumbleUpon toolbar to share it with other StumbleUpon users.
Reddit is the no frills social bookmarking site. Users submit links they like then other users vote for them (positively or negatively). The most popular posts rise to the front page for everyone to see.
Pinterest is a visual social bookmarking site where users can pin (i.e., bookmark) images, videos, and quotes on virtual pinboards. Users can like, repin, and comment on each other’s pins.
Slashdot is very popular for links about technology, science or science fiction. If your blog is about one of those topics, your submissions should do well at Slashdot. Users submit content which is then evaluated by editors before it is shared with other Slashdot users.
Newsvine’s mission is to bring big and little media together meaning traditional media sources and individuals. However, submissions are rated using several factors including reputation, freshness and and popularity, so it’s difficult for individuals to get a lot of exposure and traffic from Newsvine.
Fark allows users to submit links to content they like and want to share, but those links are evaluated by Fark administrators who determine which links appear on the Fark home page.
Technorati is typically thought of as a blog search engine, but users can also save interesting online content as “favorites” which other users can access.
Diigo has been referred to as social bookmarking on steroids. Diigo describes itself as “a research and collaborative research tool on the one hand, and a knowledge-sharing community and social content site on the other.”
Tumblr, Delicious, Bitmark