If you are regularly bookmarking your favorite sites in social book marking sites then I guess Shareholic is the right tool to make the process more simple. Shareholic is a firefox browser extension that enable users to bookmark in social sites like digg, Del.icio.us etc and share it in facebook twitter etc.
One of the main drawback is the user need to sign in before submitting it with shareholic. This is more helpful for bloggers to share it to social bookmarks. We can also bookmark the page via right click.