I've been reading an awesome book on composition and design in photography called The Photographer's Eye by Michael Freeman. There were two concepts I learned about recently that I tried to apply in this photo: "ambiguity" and "delay".
Ambiguity is simply where the image isn't obvious and straightforward, and is "slower to read". One of Freeman's examples was to focus on a subject's shadow rather than the subject itself. The viewer becomes more involved in the photograph when they have to complete it. "In a sense, it is like hearing a clever joke--just understanding the point is rewarding."
Delay is a closely related subject that I thought was really cool. The idea is that you hide an important part of the image by applying design techniques to draw the viewer's eye to other places first. Delay is essentially how you create ambiguity in your image.
When I saw this huge spider on the side of our house, and then its shadow, it seemed like a great opportunity to apply these concepts. I've tried to enhance the contrast on the rose as much as possible to make it "pop" and grab your eye first. Hopefully your eye moves next to the shadow of the spider, which gets your imagination working about the creepy critter. Finally, further scanning the frame should reveal the spider itself, though it's camoflaged and out of focus.
My biggest regret here is that the background is pretty confusing--the shadows of the leaves are a mess and I have to imagine it's hard to make out here that you're looking at the side of a house. You'll have to let me know if you think it worked!