After wanting to be able to post stuff to my facebook account from my blog for no other reason than "I Can", I looked around at the plugins that exist at the moment. The ones that I found worked but they were not what I wanted. The closest I got was the plugin Publish To Facebook. What I didn't like about this plugin was that it highjacked the publish/update button. What I wanted was the ability to press a button and publish to facebook for only the posts that choose. So I decided to write my own plugin, that add a button to the edit page to do just this.
The can for the moment the source code can be checked out from bazaar repository, then simply upload the folder to the wp-content/plugins and you're good to go. If you don't like or use bazaar you can download the tar ball.
bzr branch http://bzr.yeticode.co.uk/post-to-facebook