I remember a few beverages that're gone (Surge, Crystal Pepsi, Zima, Orbitz, etc.), but I can't say I miss any of them.
For food stuffs, I miss Necco wafers and Clove/Blackjack/Beemans gum; they're still made, but I generally don't buy food online or visit hipster candy stores. I also miss the old chili cheese burritos from Taco Bell; you can still get 'em, but I think the chili is a bit different nowadays and no fritos.