I used to love rainy days ... they were the best for opening up select windows (the ones that were well-covered and on the side of the house where the wind isn't blowing) and getting fresh air inside. It always puts me into a housecleaning mood.
These days, unfortunately, the barometric pressure changes that come along with rainstorms trigger my migraines nearly every. single. time. So now I just lie in bed, in the dark, with an ice pack, and wish I felt well enough to get up and clean house.
One of my favorite smells in the world is petrichor, that slightly metallic smell you get at the beginning of a storm where stone is wet. I don't know why, but it makes me feel at peace.