Last year, I decorated our house with giant, paper maché spiders. Due to the van-loads of children that showed up, I took this to mean that it was a success. This year, I decided to go with another theme that scares the hell out of people: Aliens, as in the movie. I planned this for at least 3 months, in my head and constructed them in about a month out of paper maché, garbage bags , sticks and paint.
We have them on the garage, over the entrance and even an Alien queen, guarding some eggs.
One of the eggs has a face hugger coming out of it, ready to nab an unlucky trick or treater. On Halloween, I plan to have strobe lights on them as well.