Email newsletters are so hot right now. Even the Original Rainbow Cone wants in on that sweet, sweet newsletter action. Yeah, they got me. I scanned the QR code and signed up, when I stopped in for a Rainbow Cone (a uniquely Chicagoan way of doing up an ice cream cone) last weekend. I won't spoil the surprise for you -- google it if you're curious. And if you, too, would like to sig…
