Julen

How much time have you spent every time you have created a table of contents manually? Or you may even haven’t do it because of the pain that it would suppose to do it manually?
With this plugin, you will be able to generate tables of contents for your posts in a completely easy, automated and personalizable way. It automatically looks for every <h*> tag, to generate the table entries for them.
Features:
<ul>
<li>Configuration of the depth level of the table.</li>
<li>Configuration of the indentation of the levels of the table.</li>
<li>Option to add to the elements of the table link to each section.</li>
</ul>

TinyMCE Table of Contents

Completely automated and instantaneous way of generating tables of contents for posts.

PiotrPress

Clearcode

The WordPress CC-TOC plugin automatically creates a table of contents (TOC) for posts/pages (and/or custom post types) based on headings in content. This plugin can also output a listing of child pages (INDEX).
The TOC by default appears before, while the INDEX appears after the content post/page.
<h4>Tips & Tricks</h4>
<ol>
<li>You can disable support for TOC and/or INDEX displaying in specific post/page edit page manually.</li>
<li>You can also use shortcode (by default <code>toc</code> and/or <code>index</code> – you can change it in the settings): 
[toc] and/or <code>[index]</code></li>
</ol>

CC-TOC

This plugin automatically creates a table of contents based on html headings in content.

TinyMCE Table of Contents vs CC-TOC