If you are a Google Buzz fan you may have found stuff around the web to share with your Buzzers. It was not so easy to do so 'cos you had to traverse to another tab or a window to do that.
First in the scene to implement Google Buzz Buttons were sites like Mashable (The first Google Buzz Button I pressed) and Techcrunch. It was not easy as they had to use Google reader as their backend.
So Google has provided, copy and paste Google Buzz buttons that anyone could implement on their sites. You can see major sites that share these buttons on the above Picture.
You can find my Google Buzz Button on the left hand Column.
Official Google Blog: Google Buzz buttons