A blazing fire in the woodstove helps my mood -- I find I get really fucken depressed when I'm cold. I make a lot of crockpot soups in the cold months, so my house smells happy. (broccolli beer cheese potato soup cooking as we speak!) Another weird trick, I like to make home made bread -- just the act of kneading the dough, smelling the yeasty smell, and creating something so tasty from a few ingredients helps me.
If I force myself to exercise -- walk the dogs, rake the leaves, chop kindling, I feel better too. Bonus points if I do this when there's a glimmer of Winter sunshine. Funny thing is, I love it when it snows here, as it's not very often, and it's still *new* to me (I lived most of my life in snow-free areas). Snow is not a depressing thing for me, but an uplifting one. It's the Oregon overcast and rain that gets me down.
I also recommend the three S'es, Shower, Sleep, Sex. Life always seems a bit brighter after one, or all, of those things.
Good luck to you!