I've been hosting some Avon holiday shopping parties, and to help make them more festive, I've covered a display area with snow –  Insta-Snow, to be exact.  It's a polymer powder that you mix with water and like magic — Snow!  It's even cold! (Thanks to the constant evaporation of the absorbed water).  When all the water evaporates, Insta-Snow returns to its powder form, easily vaccummed up or reused.  Because it is wet, you do need to be careful not to use it on surfaces that will be damaged by water, but if you need to keep it fresh for several days, just spray it with water mist and it fluffs back up.  So much more realistic than snow blankets or the dry snow crystals that you find at the craft stores. The 1lb bag makes 8 gallons of snow.  $24.98 at amazon.com; smaller quantities also available.