Del.icio.us also gives users the ability to "tag" their bookmarks with descriptive category names. For example, someone who has bookmarked multiple Web pages that deal with the Washington Nationals baseball team could tag those links with any terms they want, like "baseball," "nationals," "natsfan," etc.

As members of a "social bookmarking" community, del.icio.us sers can also see how many other people have bookmarked the same pages, and they can look at those users' bookmark collections to find other interesting online content.

To register, go to: http://del.icio.us/register

Another form of social sharing, this site also lets users categorize the content they are submitting to Digg and label it with descriptions of up to 350 characters. Digg users can also submit comments on each content item submitted to the site.

To register, go to: http://digg.com/register

To register, go to: http://reddit.com/login