Auto Fill an adress

I was looking at how to build a registration form where I could just enter in the post code of the client/registerer and it would automatically populate the rest of the address to a dropdown list.
I see many different sites have this feature and I was wondering was there a script possibly by google that does that


Anything ‘auto’ on the client side involves javascript. Populating drop down boxes, autocompletion (like google does) and things like that usually are realized using AJAX. Do a search for it in the JS forum, or google for it.

Oh i know that but what im looking is if there is a script/collection that already has this data collected.
You know if you register for something you are only asked your post code and then a list of house numbers for that is populated.
Is that list available anywhere. I cant imagine that each company ie o2, amazon, ebay etc would create their own database with all the numbers and postcodes in it. They must use some script or plugin or something