how do Google adwords vouchers work

Hi,

I have recently started using google adwords to publicize some of sites i have and I pay out the hard cash. But recently I heard about various adwords vouchers of various denominations available at very cheap price.

I am puzzled as as to how do people actually get these vouchers. Yes i have heard that some of the hosting sites provide free adwords vouchers in their plans. The questions arises in my mind:

From where do these hosting sites actually get these vouchers?

Do these vouchers work with existing adword accounts, or with the new ones only? In that case is it possible to signup for a new account every time i get a voucher? wouldn't google track me if I advertise same sites with new accounts every time.

Thanks

 

http://adwords.google.com/support/bin/answer.py?answer=8205&query=vouchers+&topic=&type=f&onClick=

 

its marketing... you spent money in advertise that you not pay.. then you will pay cause vouchers may have finished

 

vouchers are link a prepaid cards, you just enter its number in your adword account and get a balance to use.