Sidebar inside post with related posts as at BBC
It is also would be great if an in-story sidebar could be added. You may see that how it is done by bbc here. They put the titles of the related articles below the image. The titles should be manually added and must be related very much to the post. That will significantly decrease bounce rate for any website.
For example such service is provided by http://context.ly/ but it is not free. You could have you own in-story sidebar that allow to add custom posts
A possibility of disabling in-story sidebar should be added as well