Bark TutorialWe will be creating this texture:

Here's how...
Step 1: Create a new document in Photoshop, size 5x7 inches.
Step 2: Set your foreground color to #282828 and your background color to #f1f1f1
See this picture
Step 3: Grab your gradient tool and throw a linear gradient on a diagonal across the canvas so it looks like this:
Step 4: Grab the dodge tool and set the Range to midtones, the size to about 45, hardness 0, exposure: 50%. Create some streaks through the gradient like below.
Step 5: Grab the burn tool with the same settings as for the dodge tool and create some more streaks. Your image should now look something like this:
Step 6: Go to Filter->Distort->Diffuse Glow. Use the following settings:
Graininess: 3
Glow Amount: 3
Clear Amount: 15
Your image should now look something like this:
Step 7: Go to Filter->Render->Fibers. Use the following settings:
Variance: somewhere between 8 and 12. I like about 11.
Strength: choose about 3 if you want soft bark, and about 7 if you want stiffer bark. I chose 7.
Should now look something like this:
Step 8: This step is optional, but I like the effect it produces. Go to Filter->Texture->Craquelure. Use these settings:
Crack Spacing: 16
Crack Depth: 3
Crack Brightness: 10
It should look something like this:

The effect however is a bit too strong. So go to Edit->Fade Craquelure. Set the opacity to 28% and click Ok.
It should now look something like this:
Step 9: Time to add some color. Go to Layer->New Adjustment Layer->Hue/Saturation. Check the colorize box. Play around with the sliders till you get a color you like. Here's the settings I used.

And here's the final product. You can also do some level adjustments after the Hue/Saturation adjustment to tweak the darks and lights a bit more.

I hope you enjoyed this tutorial. Remember to experiment with the dodge and burn tool and the Hue/Saturation and levels to achieve a unique effect every time.