Few days ago I came across this thing: The Weathering Magazine. Second issue of it, entirely about making your models look dusty. The first issue was about rust, the theme of a third one is still a secret as far as I know. I must say that I'm impressed with this magazine. All the articles are incredibly insightful, showing the techniques in a clear, step by step way, nice and easy to understand. And the effects those guys are achieving are just incredible. Not only beautiful, but also unbelievably realistic. If you're interested in putting a realistic weathering effects on your minis/models (but not only, there's also a bunch of advice on creating beautiful, ultra-realistic bases or terrain pieces in "Dust" issue) I definitely recommend checking out The Weathering Magazine, I'm sure even hardcore veterans will find something new in each issue, amount of techniques shown is almost too big ;) I'm looking forward to trying some of the methods shown in the magazine out!