This is small yet useful thing.
I was looking to add Google +1 button to my blog, which is hosted on wordpress.com. And it doesn’t give access to edit the code .
There are many widgets available for google +1 button on web (like : http://wordpress.org/extend/plugins/google-1-widget/), but it requires to edit the code, so its not helpful if blog is hosted on wordpress.com.
Finally i fund the solution, there is a section under Settings tab in Dashboard called Sharing (Settings > Sharing) where you can find options of adding Google +1 button , facebook share/like , twitter , linked-in, print button etc. and few other options too.