Attached Link: http://www.renderosity.com/viewed.ez?galleryid=326720&Start=1&Artist=mboncher&ByArtist=Yes

I tried a "frosted needle" texture in my "Winter Cemetary" picture. If you like what you see, lemme know and I'll email you the texture. The snow covered trees were made by duplicating the trees, raising them a few BU's and making the trunk a snow material. Only other suggestion for now would be putting a treeline in the background that you can't see past, or giving some illusion of a horizon. Treeline terrain may be best because you can hide its imperfections in the snow/fog.