José Marques

Sometimes you need some extra styling and TinyMCE does not allow a lot. 
This plugin allows you to add per post or page CSS and Javascript.

Content Art Direction

Allows custom styling and interaction for posts and pages

keegnotrub

An update on the incredible Art Direction plugin by Noël Jackson (http://noel.io) and Dave Rupert (http://daverupert.com). Allows you to enter custom CSS to be applied per post/page.
Additional features include:
<ul>
<li>Optionally place span classes on your post/page title characters </li>
<li>Optionally place span classes on your post/page title words</li>
<li>Ability to responsivley use viewport units on post/page title</li>
</ul>

Artsy

Art Direction for WordPress - Allows you to enter custom CSS to be applied per post/page.

Content Art Direction vs Artsy