Out of all the amazing options, a pumpkin decorated with a spiderweb made of thumbtacks was not only our favorite, but also the easiest to duplicate.
Just buy a naturally white pumpkin - or a traditional orange pumpkin - whichever is your preference. Use a pencil to draw on a spiderweb or come up with your own creepy creation. Then fill it in with gold thumbtacks. We estimate it would take 250 thumbtacks to fill in a spiderweb design on a large pumpkin. You can find gold (and a variety of other metallic finishes and colors) thumbtacks from the Threshold brand at Target ($3.99 for a package of 25).
If you're just not a do-it-yourselfer, we discovered a trick that's a real treat. You can take your pumpkin and the materials needed to decorate it to the floral design department at Michael's arts and crafts stores and for a fee that's around $20 (depending on the size of the project) they'll do it for you.