TCBarrett

This plugin requires is just the front end javascript library, the following two things to be done in support: 
1. Add the class ‘simpleajaxform’ to your form. 
2. Make sure you have the correct wp_ajax handler hook defined.
It was primarily built as an example for a blog post.

Simple AJAX Form

A simple jQuery javascript library to ajax enable forms.

Claude

This plugin detects Ajax requests and returns just the formatted body of the post or page.

Ajax Content Renderer

This plugin detects Ajax requests and returns just the formatted body of the post or page.

Simple AJAX Form vs Ajax Content Renderer