On a Search Engine Watch forums post, a member says that he has many Google AdWords vouchers and wants to resell them.
The only problem is that they aren't for resale.
AdWordsRep, Google's Customer Associate, writes in and tells the user to proceed with caution.
Given that AdWords vouchers are not meant to be sold, I would advise against responding to any offer which offers one or more of them for sale.
He later reiterates his point:
...these vouchers are meant as a means for new advertisers to try out AdWords for a short time, on Google's nickel - not to be gleefully sold on well known auction sites - or, now, apparently, on this very forum!
Discussion continues at Search Engine Watch.