Ben Huson

If you want to spice up your theme layouts this plugin will allow you to show different parts of your content in different area of your theme templates – break out of a single column of content.
More information can be found on the <a href="https://github.com/benhuson/content-parts/wiki" rel="nofollow ugc">Content Parts plugin page</a>.

Content Parts

Divide your post content into parts that you can show in different areas of your theme templates.

Didier Sampaolo

When you write a long post, it is common to add h2 and h3 tags to create sections on a specific topic. This plug-in will search these sections and add a link to each of them at the beginning of your post. Each section will become a named anchor, allowing the user to browse quickly through your post. 
This summary is also understood by major search engines and should improve your CTR (click-through rate) by providing richer snippets.
<a href="http://www.didcode.com/code/wp-summary.html" rel="nofollow ugc">Plugin home page</a>

wp_summary

wp_summary will automagically show a summary of your post at its beginning, using h1, h2 and h3 tags to create sections.

Content Parts vs wp_summary