I nominate jp0213. Not just for his GameStop coupon threads early and GameStop trade-in value threads, but also for being one of the best CAG traders and an awesome friend.
Speedy's weekly ad posting has saved me a ton, so he's got my vote. As others have said, Marten deserves honorable mention for his incredible Child's Play raffle prizes.
It's a crime if you don't vote for Speedy. All of the other candidates are deserving, in their own right. But Speedy is a CAG institution. I can't fathom how much money he has personally saved us CAGs.