Just wanted to let you guys know this is a Thing That Is Happening. I can't find a way to contact them about an ad without an AdSense account, but your legal team should proooobably drop Google a letter about this.

In the Promotions tab of my primary gmail inbox, I have started to see ads for gil seller websites. Considering being on either side of a transaction through these is a bannable offense, I'm pretty sure you guys don't want these sites being circulated more than they already are. We have enough gil spammers in-game, I'd really prefer not to deal with them outside it, too.

Screenshot of such an ad: http://i.imgur.com/KxE1Xks.png