Stephen Paul Weber a.k.a. Singpolyma http://singpolyma-tech.blogspot.com/
Based on work by Andrés Santos
Must be able to get to the 'Edit HTML' view and paste a line of code to the <head> section.
Makes it so that hovering links in posts brings up a screenshot thumbnail of the page that link goes to.
Cut-n-paste the code from the homepage into the <head> section of your template.