Fumiki Takahashi

Hametuha INC.

Anyway Feedback provides simple controller with 2 buttons(Useful and Useless). Users can send feedback to specific post or comment.
What you get is amount of positive feed backs and negative ones per post types. Typical usage is for FAQ. You could know if your FAQs are usefull or not.
Sidebar also supported. You can display sidebar which includes the most popular posts per post type.
If you have some request, feel free to contact me. For experienced developper, I’m waiting for pull requests on github.com.
NOTICE Requires PHP 5.3 and over.

Anyway Feedback

This plugin enable users to send feedback with single click. This may support you to analyze your user's opinion. Works as a help center for your …

webdevfe

Get customer feedback, immediately! 
Use this simple widget to quickly add feedback functionality to your WordPress site. To install the Feedback Widget you would simply use this plugin. All feedbacks from your users, powerful analytics and customization can be found on your account at mBedded Widgets site. 
Prior the installation, you need to register at https://mBeddedWidgets.com to acquire the tId token. No Credit Card info is needed. It’s a quick process that should take you just a few minutes.

Anyway Feedback vs Feedback Widget by mBedded Widgets