Looking through some pictures tonight and came across this picture of "The Watcher". I think this was the first "real" Halloween prop I ever made a few years back. He was made from wood, burlap, chicken wire, monster mud, and an old mask. I usually put this guy in a dimly lit place where people have to walk right by him. In the dark it's hard to tell if it is a real person or not, and you are expecting him to grab you at any moment.
I should point out that I used the Home Haunter's Prop Building Handbook, from Terror Syndicate, while making this guy... Here's another picture of him in "action".