Living on the westcoast in basically a rainforest makes for many a rainy day. I like the sound of rain on the roof, preferably at night, but the gray overcast during the day I could do without. It tends to depress me, and we get days and days of it here in a row.
I usually open the windows, letting in some fresh air and try and get some work done in the studio. If I can't get motivated at all I retreat to the couch, with a good book and the cat.