I found this page today where you can get a $250 free Adwords Voucher.
What's the catch? It's only for people whose credit card billing address is in the US or Canada.
The free Adwords coupon offer expires on January 31st 2008.
I didn't try it but a friend told me that he managed to sign up and get the voucher using a Virtual Credit Card. He lives in Europe. So, it may work for people outside US and Canada.