There’s a good mini-FAQ on Live Bookmarks here. Check out some of the cool ideas:
Why keep your bookmarks to yourself? Services like http://del.icio.us let you publish your own bookmarks as RSS feeds, so that other Firefox users can subscribe to your bookmarks through Live Bookmarks. Live Bookmarks and del.icio.us makes it easy to share cool sites you like with your friends. … You can also put your bookmarks into your own private RSS feed, to share your bookmarks among multiple computers.