So I have heard of people hiking with an umbrella. But I was thinking about the fundamental flaw of umbrellas and the fact you never actually stand directly under the center of the umbrella like you should. Someone(probably myself) needs to make an umbrella with a handle that isn't centered. That way you can stand actually under the center of the umbrella.
Then I thought of how it could be applied to backpacking. You could attach a flap to the back that rolls up. It could then somehow unroll and loosely attach to your pack as a pack cover. Assuming you dont hike when its too windy this might work.