I managed to put some time aside and wrote a small, WordPress plugin. It displays the button at the top of a single WordPress post (but not on archives, index, etc. nor on pages; changing that though should be relatively trivial). What does everyone think of putting this button on the Fitness blog?
Here's a screenshot of what it looks like on my personal blog:
If you're interested in the code, it's available on GitHub: http://git.io/D6kj3A
Update: The plugin has been approved and is now listed on Wordpress.org.