Creepy and simple! All you need is yarn, package of webs, package of plastic spiders, and a staple gun! My big spider is made from pipe cleaners and small balls of yarn I rolled up! SOOOOO simple but soooooo creepy! For my halloween party I will be adding a strobe light at the top of the stairwell to add to the creepy-ness!
On a side note, I am planing on painting the stairwell so I went to town with the staple gun, you may want to find a different route if you dont want to fill a million little holes after halloween!