I guess my old PSU sig has me covered.
I gave in. This is as festive as you're gettin' out of me.
Awesome job guys
http://www.online-image-editor.com (Credit to Vicki for showing me)
Upload your sig, or image you want, and go to wizards (at the top of the tools) and weather > the snow is on the first page of the weather tab
And I was wracking my mind to mimic the effect in the PSU signature.
Imperator Danknovaxperaux Divi filius Imp XIII Pont Max Trib Pot XLIX Cos CXVI Primus Signiferi Box-xy Princeps Moderatores Pater Forum