nrelate
nrelate should be talked more for its consistency while displaying the relevant content to the related posts. nrelate displays the most relevant content to the users and thus helps you in engaging the visitors to your blog for more time. nrelate integrates well with Blogger, Tumblr & WordPress platforms. They also provide advertising options which will help you in earning some extra income.
Outbrain
Outbrain pulls your best posts by adding related links along with thumbnails. Outbrain widget comes as a WordPress plugin and upon activation of the plugin it will automatically inherit the look and feel of your site. Along with thumbnails, Outbrain also provides rating widget which will come included with the plugin and they will provide full statistics of the plugin performance and stats at their site.
LinkWithin
Linkwithin supplies related posts with thumbnails and integrates well with Blogger, Typepad, WordPress (self hosted) platforms.The widget is free and it takes less than a minute to get the widget up and running on your blog, no signup is required for using this plugin. But using LinkWithin plugin will show their URL in the right bottom of the widget.
WP-Thumbie
This free plugin works in a simple way, display a list of related posts along with thumbnail images of those posts for the current post and is based on Contextual Related Posts plugin for WordPress. We are really impressed with the way it shows related content, almost 80% of the time it displays very relevant content. But using Wp-Thumbie plugin will show the author’s blog URL in the left bottom of the widget (I feel that the author should provide an option to remove the URL).
Related Posts Thumbnails
As the name suggests Related Posts Thumbnails is very simple to use plugin and the admin panel allows to configure the plugin according to your needs. Further customization is allowed to suit your design needs and it is available in several localized versions.
let us know if you come across any other beautiful plugin which displays related posts with thumbnails, we love to know more.