Check out del.icio.us - a bookmarks manager. It provides a web service for sharing bookmarks - everything posted is publicly viewable, so its not a tool for storing private collections.
del.icio.us is a social bookmarks manager. It allows you to easily add web pages you like to your personal collection of links, to categorize those sites with keywords, and to share your collection not only among your own browsers and machines, but also with others.
Find out more https://del.icio.us/