Zinio offers $50 in Zinio Bucks for free, good for 18 single issues or 6 mini-subscriptions. That's tied with our January mention as the best such offer we've seen from this digital newsstand service. When you enter your name and email you'll receive a unique code. The code can only be redeemed via the Zinio web store; it won't work if entered via the iOS or Android apps. (During checkout, enter the code in the "Service Credit or Gift Card code" field.) The credit can't be used with Paypal payments. Deal ends June 30; credit expires August 8.