One of the most common uses of vertex information is by creating more realistic-looking terrains or environments. This is done by using each channel of the RGBA vertex color to blend into different textures. This is very efficient since you don't have to import yet another texture to blend into the other textures. You'll see this technique in just about every game that deals with outdoor terrains and structures.
This particular recipe will demonstrate a more advanced way of performing this blend by using a grayscale image or heightmap to add more detail to the vertex blending.
Let's take a moment to get our scene together and gather a few textures we will need: