SideNails allow you to display a list of the last posts with a thumbnail, in a widget. For this, SideNails use the images linked to your post (thumbna
SideNails was first developed for my own use. But I think it could be useful to someone else ;) Basically, SideNails can do one thing : - get an image from your post, and use it in a widget to make a thumbnail link to this post.
Of course, you can customise the "last post" : you can setup the number of posts shown, and also filter these posts by categories and/or tags. The images used to make the thumbnails can be from the post'media library, a post'featured image, a NextGen Gallery linked to the post, or a custom fields where you setup the link to this image. You can also change the default size (even if it's not recommanded) to your choice.
In bonus, there is also a specific template to be used with YARPP Plugin. It allow you to display the related links with the same thumbnails.
Note on the support : For better support, I will only answer question/suggestion/etc through a dedicaced page on my website : http://www.tranchesdunet.com/sidenails You can post either in english or french (preferably).
Feel free to test it and report any bugs/suggestions