BibSonomy is a social bookmarking and publication-sharing system. It aims to integrate the features of bookmarking systems as well as team-oriented publication management. BibSonomy offers users the ability to store and organize their bookmarks and publication entries and supports the integration of different communities and people by offering a social platform for literature exchange.

Both bookmarks and publication entries can be tagged to help structure and re-find information. As the descriptive terms can be freely chosen, the assignment of tags from different users creates a spontaneous, uncontrolled vocabulary: a folksonomy. In BibSonomy, the folksonomy evolves from the participation of research groups, learning communities and individual users, organizing their information needs.

Publication posts in BibSonomy are stored in the BibTeX format. Export in other formats such as EndNote or HTML (e. g. for publication list creation) is possible.

The service was developed by a team of students and scientists working at the Institute of Knowledge and Data Engineering and is hosted by the University of Kassel in Germany.

[Description taken from the Wikipedia article about BiBSonomy]

Listango is a free online bookmarking app. Users can save links to web pages and articles using a bookmarklet, organize their links into public or private lists, and share links with friends using Facebook, Twitter or email. Because it is web-based, users can access their bookmarks from any device, anywhere. Listango also offers a free IOS bookmarking app.

Listango is designed to work on all modern web browsers, including Google Chrome, Firefox, Safari, and the latest version of Internet Explorer.

Pinboard is a social bookmarking website that describes itself as "a fast, no-nonsense bookmarking site for people who value privacy and speed." The service lets users bookmark content from any web browser, offers browser plugins, and a way to save open tabs in a minimal, fast, and secure environment.

You can connect up to three Twitter accounts (search the archives of your tweets), and configure Pinboard to automatically mirror public bookmarks from your accounts on Instapaper, Pocket and Readability. All of your bookmarks from Delicious, Google Bookmarks, Diigo, Firefox, Safari, and many other sources can be imported to your Pinboard account. Everything on the site is available as an RSS feed and you can import and export data in a wide variety of formats.

Unlike other popular bookmarking services, Pinboard caters to users who value privacy. You do not need to have any public bookmarks to use the site. Pinboard does not serve any third-party content to logged-in users—that means no scripts, images, analytics trackers, and no ads. You do not have to provide any personally identifying information to open a Pinboard account. The only requirement is a working email address.

There is a third-party clients.

There is a one time fee of $11.

In addition to the basic features, Pinboard offers a bookmark archiving service for an annual fee of $25. The site will crawl and store a copy of every bookmark in your account, and display a special icon you can click to see a cached copy. If the page you bookmarked goes offline, you'll still be able to see the archived copy indefinitely.

Pinboard is a small site that features easy access to customer support and communicating with the developer. He is easy to reach through Twitter, IRC or email,.

Blackboard Scholar is a social bookmarking service customized for education. It allows students and instructors to find educational resources on the Web. Available only to users of the Blackboard Learning System.