ujCodePlay provides html, css and javascript "code playgrounds" (similar to CodePen, JSbin, etc) to profiles. A code play can also be embedded in the TinyMCE editor using jrEmbed.
In a page, a code play is editable - you can mess with the code displayed and see the changes immediately. It's a great way to demonstrate code snippets and allow your users to play with them to figure out how the code works, or to ask them to provide an isolated example of a problem they are seeing with their html, css and javascript.
There are three views and a range of styles to choose from in the module config.