xsaber

This plugin will show a testimonial feed with star rating on your post, page or widget area using the shortcode <code>[tfeed_output]</code>.
Parameter: 
count: limit the number of feeds to show. (default: 4) 
Usage: <code>[tfeed_output count=2]</code>
I am planning to add pagination and front-end testimonial rating submissions in the next updates.

Testimonial Feed

A Simple WordPress Testimonial UI with Star Rating

wokamoto

Adds a new type of feed you can subscribe to. 
 http://example.com/feed/json or <code>http://example.com/?feed=json</code> to anywhere you get a JSON form. 
 http://example.com/feed/json?callback=callback or <code>http://example.com/?feed=json&callback=callback</code> to anywhere you get a JSONP.

Feed JSON

Adds a new type of feed you can subscribe to.

Testimonial Feed vs Feed JSON