If you have Photoshop and you aren't working with textures, then you should be. They are a great element to add to your pictures for an extra "kick".
Shadow House Creations has some great textures and tutorials on how to use them. The best part? They're all free!
Check out these two pictures.
The first has been edited, but textures have not yet been applied.
In the second picture I used Shadow House Creation's textures and this tutorial to make this picture.
Check out the rest of Shadow House Creation's blog here.