Del.Icio.Us: Bookmarks Online Library

https://del.icio.us/ it's not only a bookmark manager, it allows to multicategorize your links with tags. You can share links with other members, and there are nice Javascript hacks to allow posting links from almost every browser. (Found via migs)

Once you have some tags, you can find the visual effect here https://kevan.org/extispicious.cgi?name=rido