Is there any module that can show whoever edits a node, just like how happens on Stack Exchange sites, where the user who edited a post is shown together the author of that post?
This article should be able to help you: Adding 'Last edited by name some time ago' information
I'm not sure how you want it to look exactly, but with a preprocess function and a simple template edit, you can add an editors information. You can style this however you like and add/remove information, but to show the editor's name and the edit date/time do the following:
Add to template.php (or add the code to the preprocess_node function if already exists):
In your tpl file (node.tpl.php, node-YOURTYPE.tpl.php, etc):
You might be looking for the Diff module, or any revision module.
Here is a quote about it (from the module's project page):