Example of the Google +1 Button API
1) Click the +1 button here:
2) It usually takes 15 seconds before the API updates, so wait a moment and then refresh the page, and this counter will now be updated:
+1s for this page =
Get the code
You can read how to use this API yourself and get the source in my blog post about the Google +1 Button API. This includes a spreadsheet you can use without having to code anything yourself.