Eat Macaroni and Cheese - I don't care if it's a thousand degrees outside, rainy days make me want comfort foods, but since I don't want to leave the house to get something like chicken and dumplings, I usually end up with Mac and Cheese from a box!
Watch Movies - Particularly movies I haven't seen in a while. I love that the chances of my getting interrupted or needing/wanting to go somewhere are substantially lessened during rain.
Take a Nap - Naps are always wonderful, but listening to the rain pounding on the roof somehow makes it so much better!
Write - Blogs, journals, fiction, sermons, letters, lists, it really doesn't matter. Something about rainy days inspire me and make me want to write even more than I normally would!
Organize - On the very rare occasions that I don't revel in the freedom to do nothing on a rainy day, I feel the need to be productive inside the house and do the things that are normally overlooked. Usually this means finding some sort of dark corner to organize, especially in the kitchen.
What do you love to do when the sky turns grey and the bottom falls out?