Delicious: http://www.delicious.com/ Bills itself as “The tastiest bookmarks on the web.”
Symbaloo: www.symbaloo.com and SymbalooEDU www.symbalooedu.com I’ve seen this bookmarking tool described as a “dashboard" or “start page” and I think these are great descriptions of this bookmarking tool. A place to focus students' attention on pre-selected websites/resources.
Diigo: www.diigo.com Diigo is a powerful research tool and a knowledge-sharing community. The Diigo toolbar simplifies the bookmarking process.
Livebinders: www.livebinders.com Calls itself "your 3-ring binder for the web." To create your own LiveBinder all you have to do is add the 'LiveBinder it' bookmarklet tool to your favorite browser.
Google Bookmarks: https://www.google.com/bookmarks Google Bookmarks is primarily a private bookmarking tool with some public elements added on. Most of the other bookmarking tools focus on sharing resources with others.
PortaPortal Your bookmarks online and accessible from any machine anywhere. No toolbar with this resource. You copy the URLs to your portal.
Not happy with the choices above? Check out a multitude of bookmarking tools at webtools4u2use. Happy bookmarking!