Thanks for all the comments, I'm really pleased people have liked this article. About the snow:
I normally will carve the rocks for the base using insulation styrene (the stuff used for GW's big battle boards you get in their stores) and a scalpel. I may use various other miniatures to further embelish the base. Then I paint the rocks and use a variety of woodland scenics flocks for the various vegetation, you can get this from a model railway store. Once I have the base the way I want it, I mix woodland scenics snow with slightly watered down PVA glue into a thick paste. Then I dab this paste onto the base wherever I want the snow to be. I then let it set for a while. If I want to give the appearence that the snow is melting, I will usually give the edges of the snow area a thin wash of vallejo smoke. For the water/ icicles I use Woodland Scenics water effects, it's like a thick glue that dries clear. You just squeeze some out where you want it and use a sculpting tool to sculpt ripples where you want them. If you want the water to look sparkly like with Agyar's base, paint a river using inks and pearlecent medium, then apply the water effects. You can use very thinned down inks over the top of the water effects to bring out the ripples a bit more, but I find it's best not to overdo it. A quick word of warning, avoid imperial purple! it leaches out into the snow/ water areas and creates a bright purple spot (as on Syriak's Croissant). This is also a problem with using black writing ink. I'll hopefully be doing a step by step guide to snow bases at some point in the future.