Google introduced a AdWords Credit Card a few months back. It is aimed at giving AdWords advertisers more and longer credit towards their advertising purchases.
The initial pilot of the program included over 1,400 businesses in the U.S. Now Google is ready to expand that. Google has "recently begun to invite more businesses in the US to sign-up for AdWords Business Credit."
Google is also looking to expand it beyond the UK and the US, to other countries.
Here is a video on how it may help you:
Forum discussion at Google+.