Update: A winner has now been found - see the bottom of this post for the answer, and thank you for playing everybody! :)
Can you guess what this is? (If you've read my book on macro photography, you're disqualified from entering, as it contains the answer ;)
To help you along a little bit... The photo is taken with a Canon MP-E 65mm lens. That's a particularly epic lens for macro photography; it starts at 1x magnification, and goes all the way to 5x. On a crop-sensor camera, you get even better effective magnifications, obviously... It's really good fun to play with, actually; if you get a chance, try to rent one from a camera rental store for a few days.
For this particular photos, I used the twin-flash kit on the lens as well. The exposure was 1/90th of a second at f/2.8 and ISO 100. I believe it is taken at around 4x magnification. The only editing is a slight crop, some sharpening, about 20% desaturation, and about 30% extra contrast.
So, in a week, there were exactly 200 people who guessed; and of those, only the 20th and 73rd guesses were correct.
The guesses were overwhelming; more than three quarters of you guessed it was paper... Which was correct, in a way, but you failed to specify what kind of specific paper it was, so I'm afraid I can't accept that as the right answer...
The photo above is of a cigarette (Specifically, a Marlboro Light, I believe). The faint lines on the side are from the cigarette factory, and the brightness at the top of the image (and the darkness at the bottom of it) are due to the curvature of the cigarette itself.
However, only Harald Halvorsen and Jon Garrett guessed correctly. Since there were only two people who got it right, I've decided to give both of them the first prize; Harald or Jon, if you're reading this: You'll have an e-mail with instructions how to claim your prize waiting for you in your in-box!
To everyone else: Well done, and thanks for playing! :)
Here's a photo of the tobacco from inside the cigarette: