del.icio.us/help/firefox

This has to be my alltime favourite firefox plugin:

NEW del.icio.us Bookmarks for Firefox

All the power of del.icio.us is now in your browser. The del.icio.us Bookmarks for Firefox extension replaces your Firefox bookmarking experience and gives you a better way to ...

• organize your bookmarks
• collect and retrive lots of bookmarks quickly
• access your bookmarks collection from any computer

Cool new features:

• Quick searching of your bookmark's tags, titles and notes
• Get to all your bookmarks and tags in the new sidebar
• A new bookmarks toolbar with two views for quick access to your favorite bookmarks.

del.icio.us/help/firefox