On this page you will find lots of additinal demos I found interesting. Starting from beginner (to help you get the rough idea) to an advanced examples - cool enough to be used on live site. It is important to mention that this widget is about Javascript only (client side). However, for your convenience I also included sample PHP scripts. These simple examples will show you how to distinguish AJAX requests and extract Rate value from POST data. The server side authentication and database post-processing is beyond this article.
NOTE: All examples here will load inside IFRAME element. To view the source code, you may need to open it in a separate window, or download all examples here