Del.icio.us

[Delicious] is one of the most popular social bookmarking web services which users store, share and bookmark web pages. The source code of website is not available but user can download his or her own data through the site's API. By default posts to del.icio.us are public and can be seen by other users but it is also possible to post private bookmarks. The site is not focused on storing private bookmark collections. Del.icio.us was founded by Joshua Schachter in 2003 and Yahoo! acquired in 2005.