Adding Texture to your work

The Image above is a vector drawing in Illustrator, but was made to look a bit more sophisticated through the use of adding textural overlays.
Here is the tutorial to apply the textures:
http://vector.tutsplus.com/tutorials/illustration/how-to-create-a-textured-vector-landscape/

A great place to find HIGH RESOLUTION textural overlays:
http://lostandtaken.com/gallery