I've never actually read any of Lovecraft's stories; I've been too scared to and it is all because of this radio show. It even made me afraid of whip-poor-wills for a while.
It isn't really that scary, to be honest. But it is chilling. It gets into your mind and nestles there next to the imagination, whispering to it and allowing it to run away with all kinds of unsavory images. Even now, I get chills when I listen to it.
If you've about 30 minutes to spare, I recommend giving it a listen and I dare you not to shiver when you hear the voice of Wilbur Whateley demanding the incantation, or when something unmentionable calls out to its father.
Don't pay any attention to the slide show that come with the videos, just listen and let it sink in.
Happy Halloween! Don't let the Elder Gods haunt your dreams.