Free Warframe 3-day Affinity Booster
They usually send these out to these sites to give out every major update. Must register for a mmohuts account to claim a key. Past free keys have had no expiration. Boosts your affinity gain x2 for 72 hours upon activating on your Warframe account.
They also gave them out here, but ran out: http://www.mmorpg.com/giveaways.c...a