Wood Tutorial for Photoshop CS
13. Select Filter>Distort>Wave.

14. Use the settings shown above.
15. Select Filter>Distort>Ripple.
16. Set the Amount to -75%.
17. Set the Size to Medium.
18. Sharpen the image (Filter>Sharpen>Sharpen).
19. Select Filter>Noise>Add Noise.
20. Set the Amount to 0.78%.
21. Set the Distribution to Gaussian.
22. Make sure Monochromatic is checked.