As reported by Danilo Campos on Twitter "Any ziplock bag you happen to find in your kitchen will waterproof your phone while allowing the screen to respond." So I gave it a whirl and it works!
Neven Mrgan, who I heard this through, brought up a few great uses for this. He said "This means I can use my iPhone when I walk in the rain. I can read recipes off it in an oily, wet kitchen. I can follow crafting tutorials, paint all over my fingers."
Back when I had dead spots on my iPhone's touchscreen I was told by the Apple Genius at the store said that any moisture making it underneath the touchscreen could have been the cause. After thinking of the ways I could have gotten moisture into the iPhone I realized it could have been sweat when answering the phone while working out and playing basketball. From now on I'll be putting my iPhone in a baggy when making sweaty phone calls.
The possibilities are now indeed endless.