Looking for the code to build a Ranking Meter (eg. NetFlix)

I was wondering if anyone has developed the code, or has a general strategy, for creating a "ranking meter".  This would be similar to the "star system" used by Netflix or Amazon for ranking the popularity of an item. 

In the case of Netflix, when a user passes their curser over a set of 5 stars, they have the ability to click on one to select it (1 star, 2 stars, 3 stars, etc.).  They light up in sequence as the cursor moves from left to right.  I assume this is probably a set of rollovers and submit buttons connected to the images?  I also assume it is javascript code that takes the click a sends a value to the dbase on the backend? 

I would also like to build a similar function to display what the average score is for an item is after users have ranked it.  This is what you see with Amazon.com for book rankings.  I see there is also a meter on the top of this suggestion.     I assume that this just the passing of a value from the dbase to the page, and having the javascript choose the right image (1 star, 2 stars, etc.) based on the value (1, 2, 3, etc).

I also assume these two functions are related.  My knowledge of Javascript is growing, but the devel is in the syntaxt for me :-)  If anyone has already done this, or knows where I can find the code, it would be greatly appreciated.

Thanks,

Bob