I've been working on the weathering techniques and colours for my winter themed Imperial Guard army. Not that I'm going to get to it any time soon -- but it was a good excuse to practice vehicle weathering and snow application.
The snow is PVA, water and baking soda. The mud was applied using water, pastel pigments and PVA; I also dipped the brush in static grass every now and then for additional effect.
Additional stowage is from Venderlein -- although I'll apply it differently on future vehicles and not add any cloth to the hull. It's snowing, raining and horrible -- not so much "put your backpack on the tank" weather.