How to make good looking Dust in blender.

This tutorial is kind of different than others that have been presented. I think Sgefant said it best when he said its a Meta Tutorial. Basically I'm going to give some brief introductions to topics with links to more detailed information. There is a lot out there and Dust is a complicated subject. I encourage you to play with the settings in each of the areas and see what you can come up with. I'm also going to assume you know the basics of the blender interface. I'll provide some pointers but I'm not going to explain how to add an object, scale it etc...

Why Dust?

Various weather conditions. Snow/Rain/Sand-storm/Volcano's/Tornados. Or just to show that your objects have been exposed to the elements a bit and they aren't a shiny piece of metal that has never been scratched.

The Key:

You want a mixture of techniques just like with building a material. You take a bunch of things and add them together.
Our building blocks for dust:
Were going to use the following city.blend file as an example. I live in Minnesota so were going for a snow look here but its basically the same thing. Were going to transform this to this:
cityorig.jpg cityfinal.jpg

Using the above techniques I turned this into this in a few minutes:
cubestart.jpg cubeend.jpg

Here is the blender file cube.blend