Simple, embeddable tools can be one of the most powerful tool in an API evangelists toolbox. While there was a wide variety of forces that were at play in the social API evolution, contributing to the success of Twitter and Facebook, embeddable buttons, badgers widgets definitely played a leading role.
One embeddable implementation that will go down in history alongside the Twitter share button and Facebook like button, is the Github Ribbon. The Github Ribbon is the thin little ribbon you are increasingly seeing on projects, sites and applications (notice them rolling out across the API Evangelist network), letting you know you that a site's source is available on Github, and available for you to download or fork.
Github has created a simple page where you can find an assortment of embeddable Github Ribbons, in multiple colors and positioning. If you are not satisfied with the colors, they also provide the PSD and even the original font that is used. A complete, fully branded, embeddable tool that encourages use.
While I actually prefer the simplicity of the Github Ribbons, my only suggestion to Github would be to either provide JavaScript version or tracking image version, that would allow each Github Ribbon to ping home. You could also integrate with the Github API to offer tighter repository integration. Think of the network visualizations you could create, mapping out the distributed world of Github implementations across languages, countries, etc.
Even without the tracking and API integration, Github Ribbons is an extremely powerful approach to branding, and great example of using embeddable tools in the wild.
