Bainternet

This Plugin lets you add the new Google +1 button to your site or blog automatically in your posts or pages.
Main features:
<ul>
<li>Automatically button to posts, pages.</li>
<li>Easy configuration screen.</li>
<li>Four display styles (standard, small, medium, tall).</li>
<li>Show \ Hide count.</li>
<li>Over 40 languages to choose from.</li>
<li>Use as shortcode.</li>
<li>Use as template tag for easy integration with your theme or plugin.</li>
<li>Use in widgets.</li>
<li>
any Feedback is Welcome.</li>
</ul>
check out my <a href="http://en.bainternet.info/category/plugins" rel="nofollow ugc">other plugins</a>

Simple Google +1 Button

This Plugin lets you add the new Google +1 button to your site or blog.

dantaylorseo

This plugin adds a ‘Add [author_name] on Google+’ button to the end of every post. Simply add your Google+ ID to the ‘Your Profile’ area of the Admin.
<ul>
<li><a href="http://www.seowned.co.uk/wordpress-plugins/add-an-add-to-circles-button-to-your-wordpress-posts/" rel="nofollow ugc">Google+ Author Button</a> plugin homepage.</li>
<li><a href="http://twitter.com/dantaylorseo" rel="nofollow ugc">Follow @DanTaylorSEO on Twitter</a>.</li>
</ul>

Google+ Author Button

This plugin adds a 'Add [author_name] on Google+' button to the end of every post.

Simple Google +1 Button vs Google+ Author Button