This is a fantastic tutorial with a movie as well. If you like the illustrative side of photography, you should check this out.

This article has a great little Photoshop tutorial on adding texture. The writer uses and illustration, but you could certainly do this with a photograph as well. Take a look.
Add Stock Textures to Images for extra ‘Oomph’
In this little Photoshop tutorial we’ll be designing a quick art piece, then we’ll be adding some texture to [...]