Or there's my all time favorite - the cheesecloth ghosts. Pretty simple but can be messy. I like to use liquid starch, and a balloon taped to the top of a paper towel roll, to make the forms. After drying, the kids will have a blast making the faces.
There's a neat variation of the cheesecloth ghosts and similarly made but much scarier. Be creative with what items you wrap and with the amount of cloth that you use for the cover. If a little something shows through, it may add to the effect. These would look great, inside and out. They will not hold up to moisture or rain but a covered porch or home entry way would be perfect. Move them out on the spooky night if the weather allows.
This is a great variation of the cheesecloth ghost but with the use of chicken wire and glow in the dark paint. This isn't a project for the toddlers in the family but with a little adult help, most other kids will love this.
That's a start on the Spooky Day decorations. More and more ideas for the entire family still to come.