Every article on PopSci.com now features icons at the bottom of the page that allow you to bookmark or share the article with an assortment of popular web applications and news sites.
"Digg is a user-driven social content website. Ok, so what the heck does that mean? Well, everything on digg is submitted by the digg user community (that would be you). After you submit content, other digg users read your submission and digg what they like best. If your story rocks and receives enough diggs, it is promoted to the front page for the millions of digg visitors to see." -digg.com/about
"del.icio.us is a social bookmarking website—the primary use of del.icio.us is to store your bookmarks online, which allows you to access the same bookmarks from any computer and add bookmarks from anywhere, too. On del.icio.us, you can use tags to organize and remember your bookmarks, which is a much more flexible system than folders.
You can also use del.icio.us to see the interesting links that your friends and other people bookmark, and share links with them in return. You can even browse and search del.icio.us to discover the cool and useful bookmarks that everyone else has saved—which is made easy with tags."—del.icio.us/about
Netscape is another user-driven news site, similar to digg.com.
"reddit is a source for what's new and popular on the web -- personalized for you. Your votes train a filter, so let reddit know what you liked and disliked, because you'll begin to be recommended links filtered to your tastes. All of the content on reddit is submitted and voted on by users like you."—reddit.com/help
"Fark.com is a community website created by Drew Curtis allowing users to comment on a daily batch of news articles and other items from various websites. Links are submitted by Fark members, which are then approved for posting on the main page by admins."—Wikipedia
"News for nerds. Stuff that matters." —slashdot.org/about.shtml. The clearing house for all things sci-tech on the web, Slashdot takes user-submitted links and selects the cream of the crop to appear on the front page.