Defintion: Social bookmarking is a method for Internet users to store, organize, search, and manage bookmarks of web pages on the Internet with the help of metadata, typically in the form of tags that collectively and/or collaboratively become a folksonomy.
A long-standing platform that is hugely populated by researchers in the arts/tech/sci fields. Scholars and students can benefit from being able to follow the research paths and browsing habits of the scholars they are interested in.
http://delicious.com/ludiljepo -- Trudy Lane
Many others such as Ma.gnolia, Faves, CiteULIke & Stumbleupon.