Add Link to Facebook is a plugin by M66B that automatically add links to posts that are being published to your Facebook wall or pages. Simple one time setup and forget. Just two fields to fill in. The way links appear on Facebook can be customized.
The link title will be the post title. The link description will be the excerpt, or part of the post text if there is none. It is possible to configure a link image (WordPress icon, featured image or custom image) or you can let Facebook select one automatically. It is possible to exclude individual post links from being added to your wall or pages by ticking a check box just above the publish button. There is support for multi user and network sites and shortcodes will be processed. It works for remote publishing too, for example from Android or iOS powered devices or using Window Live Writer.
Pugin requires PHP 5 and WordPress 3.0 or later.
Download and info: http://wordpress.org/extend/plugins/add-link-to-facebook/