The bookmark data are stored in a database in the server.
Each user can search their bookmark database very easily.
Bookmarks can be arranged in folders in any depth.
For each bookmark, visit information is managed such as the visit counter or the last visit time, etc.
Import from or export to the local browser bookmark (Netscape, Explorer, and Opera).
Support multilingual users.
Users can set their own preference.
You can access to your firend’s bookmark tree.
Clipboard, Trashcan, History Layer, Calendar, and more.

bookmark4u sourceforge.net

Another one
online-bookmarks