Oyax is a social bookmark manager. It allows you to easily add web sites you like to your personal collection of links, categorize those sites with keywords, and share your collection not only with your own browsers and machine, but also with other people
Why donate your bookmarks? GiveALink is a public site where people can donate their bookmarks to the Web community. Bookmarks are analyzed to build a new generation of Web mining techniques and new ways to search, recommend, surf, personalize and visualiz
aghop.ORG allows you to relate categories on the web so others to hop your personal web and for you to discover related categories that other people find useful!
Del.icio.us competitors, who try to get users by paying them. In my opinion this won't work as most users, that try blogs and social bookmarking either don't want to have an adsense account or don't understand what it does.
Diigo is about "Social Annotation", a superset of social bookmarking. We believe that the social annotation service provided by Diigo can really enhance your experience for online browsing and interactions, and for information gathering and sharing.
A. Hotho, R. Jäschke, C. Schmitz, and G. Stumme. Proceedings of the Conceptual Structures Tool Interoperability Workshop at the 14th International Conference on Conceptual Structures, page 87--102. Aalborg University Press, (2006)subtag-supertag.
M. Hassan, A. Karim, S. Manandhar, and J. Cussens. ECML PKDD Discovery Challenge 2009 (DC09), 497, page 85--97. Bled, Slovenia, CEUR Workshop Proceedings, (September 2009)
M. Nentwich. ita-Manuskript, ita-09-02. Institut für Technikfolgen-Abschätzung an der Österreichischen Akademie der Wissenschaften, Wien, (November 2009)