Twitter is a free social networking and micro-blogging service that allows users to send updates (otherwise known as tweets) which are text-based posts, ranging up to 140 characters long.

Facebook (branded as "facebook") is a social networking website launched on February 4, 2004. The free-access website is privately owned and operated by Facebook, Inc. People can also add friends and send them messages, and update their personal profile to notify friends about themselves.

LinkedIn is a business-oriented social networking site founded in December 2002 and launched in May 2003 mainly used for professional networking.

Flickr is an image and video hosting website, web services suite, and online community platform. It was one of the earliest Web 2.0 applications. In addition to being a popular Web site for users to share personal photographs. Its popularity has been fuelled by its organization tools, which allow photos to be tagged and browsed by folksonomic means.

Last.fm is a UK-based Internet radio and music community website, founded in 2002. It claims over 21 million active users based in more than 200 countries.

Items in Google Reader can be shared with other Web users. Previously this was done by sending a link through e-mail, directing the user to the shared article; or by creating a basic webpage that includes all shared items from a user's account. In December 2007, Google changed the sharing policy so that items the user marked as shared were automatically visible to their Google Talk contacts.

Xbox Live is an online multiplayer gaming and digital media delivery service created and operated by Microsoft Corporation. It was first made available to the Xbox video game console.