Make a Marshmallow Blow Gun out of PVC Pipe. To shoot, simply stick a mini marshmallow in the end of the gun and blow. The amount of air power is important. This would definitely make a great project (Bottle Rocket Pvc Pipes)
This isn't MY door, but I did this too. Unfortunately, I didn't get a picture of it though. I used an inexpensive, green, plastic table cloth and a Sharpie to make a giant Creepr face. Put on front door!
Balloon arrangement for minecraft themed party. To avoid using helium, I'd make the Creeper balloons upside down, hang them all from strings (fishing line? White balloons with white streamers would make great Ghasts as well.