Again from our craft Diva Martha Stewart:
Use a pumpkin incense burner to suggest the cozy scent of pie just out of the oven. Cut off the pumpkin's top and scrape out the innards; carve round vents with an apple corer. Rub cinnamon or pumpkin-pie spices onto the lid, or push cloves into it. With a lighted tea light candle inside, the pumpkin will give off a lovely fragrance for about six hours.