SnowScape is a PhotoShop plug-in for creating piles of snow, dirt, sand, gooey, slimy stuff, blood and similar effects to your (semi-)transparent images.

You can specify where you want the snow to appear, how sticky it should be, allowing you to control whether the slopes should be smooth or jagged, and of course how much will have to be falling down.

Besides all those boring white flakes seen so often during Christmas time you also get the option of choosing a different color for you snow, allowing you to simulate cool effects such as this cool radioactive goo shown on the left. Adding a roughness option finishes it off by making it look more natural.

All you need to do to use this plug-in is create a layer in your graphics application which has (semi-)transparent parts. Snow, of course, can only fall where there's nothing there and it will stop only when it finds fully opaque areas, passing by and perfectly coloring any transparent areas so your anti-aliassed edges will remain smooth.

As a fun extra there is also an option to let you watch the snow stack up in layers.