These sites all have different approaches to bookmarking, so check them out, and find the best one for you. Some are meant for use on your site, and some are meant for allowing you to store your bookmarks acress the web.

• Delicio.us basically makes bookmarking buttons and add-ons for your browser or website. With their Hotlist, you can see the most popular bookmarks on Delicious. A very big network of bookmarks.
• Evernote can be used for creating text and ink notes, to snapshots of whiteboards and wine labels, to clips of webpages. Lets users capture anything from their real and digital lives and find it all anytime. For free.
• Addthis makes sharing easy for blogs, websites etc. Add the buttons to your site, and let users easily bookmark it, or send your link to others. Free.
• Wibiya enables blogs to integrate services, applications and widgets of their choice into their blog through customized web-based toolbars. Rests at the bottom of the screen, includes Facebook, Twitter, chat, rss and lots more.