Thankfully there are plenty of free open source JavaScript codes for gathering user feedback. These may appear as toggle boxes at the bottom of the screen, or possibly as a modal popup window. The whole point is to catch people’s attention quickly and let them know you(the webmaster) are looking for their opinion. These free JS scripts and plugins should help you get started on the right path.
UserVoice
Satisfaction
Feedback Me
Contactable
Google-Style Feedback
feedBackBox
Website Chat
Opinion Lab
Feedbackify
Concept Feedback
UserEcho
