On this page I use the AddThis JavaScript library to add buttons that allow the page to be shared on Facebook/Twitter. If you click on the Facebook button it shows the following preview of how the content will be posted to Facebook:
Notice that the image that is displayed in the post preview is the AJAX loader that is used on the site, i.e. an image that is displayed while an AJAX request is in progress. I don't know why this is being chosen as the image to be displayed in the post, is it possible for me to specify which image is used?
Here's the markup that I use to display the sharing buttons:
<div class="addthis_toolbox addthis_default_style addthis_32x32_style" style="width: 135px;">
<a class="addthis_button_preferred_1"></a>
<a class="addthis_button_preferred_2"></a>
<a class="addthis_counter addthis_bubble_style"></a>
</div>
<g:javascript base="http://s7.addthis.com" src="/js/250/addthis_widget.js#pubid=xa-4fcaa48b0ffdb7b9" type="js" />