Does anyone know of any techniques, filters, tutorials, etc. that might be helpful in recreating a realistic  painted surface in Photoshop?

 I'm creating texture maps in Photoshop for buildings. Some areas of the buildings are flat, single colors. First I fill the area with the color, but then need to add some "texture" to the area to make it look more realstic simulating surface texture, weathering, etc. Using the noise filter helps but I'd like to have more control and more options. For example, it would be helpful to be able to change the grain size of the noise.