After submitting my second photoshop modification to the Photoshop Contest thread, I got a few questions regarding the carbon fiber look. Well, I wrote a brief tutorial on it, and you may be surprised at how easy it really is.
Step 1: Go to File -> New, make a new image, 100x100 pixels, RGB color, white background.
Step 2: Fill the new image with pure black (#000000.)
Step 3: Selecting the Rectangular Marquee tool, change it's Style from "Normal" to "Fixed Size," and change the dimensions to 8 x 2 pixels.
Step 4: Click anyplace in the image, and your selection will automatically size itself.
Step 5: Now, using the Zoom tool, zoom in to 1600% exposure (the maximum Photoshop allows.)
Step 6: Using the pencil tool, color your selection white in a checkerboard fashion; as shown in the following picture:
Step 7: Define this selection as a pattern, by going to Edit -> Define Pattern, and name this pattern "Carbon Fiber."
Step 8: Now, open an image you'd like to apply a carbon fiber look to, and carefully trace the object with the Polygonal Marquee tool. (2nd from top, in left column)
Step 9: Once you've got the object selected to your liking, go to Image -> Adjust -> Desaturate. Notice how the object loses its color (if it had any to begin with.)
Step 10: Image -> Adjust -> Brightness/Contrast. Slide your Brightness bar to the left to give it a darker gray color. This will serve as the "background" of your carbon fiber modification.
Step 11: Layer -> New Layer. Name this layer anything you'd like ("Carbon Fiber" would be fine, for organizational purposes.)
Step 12: Making sure your marquee is still active, go to Edit -> Fill. From the "Contents" drop box, select "Pattern." Find your new Carbon Fiber pattern in the selection list (should be at the very bottom, since it's the last pattern you've made.)
Step 13: Click OK to fill your selection. Of course, it doesn't exactly look too much like carbon fiber just yet...
Step 14: In the Layers tab (click Window -> Show Layers if you can't find it,) drag the "Opacity" slider (located near the top of the Layers tab) slowly to the left, decreasing it to around 20% or less. Adjust this to your liking; I find that 10% - 20% works best, depending on the shade of gray you chose.
Step 15: Close your marquee and check out your new carbon fiber hood/door/mirror/dog/whatever you changed!