My favorite outside Halloween decoration is to gather leaves and scatter them by the front door and along the walkway for the kids to scuff through. I always get a few comments about the leaves. Most people are baffled about where they came from in a yard filled with nothing but cacti!
This year I gathered them up at Mt. Lemmon the week before Halloween and was lucky enough to catch the trees in a golden glory. No words necessary.
And finally, floating candles that looked very cool in the dark.