Over the last few naptimes, I've created a list of every single drop-in (mostly) free activity I can find within a short walk or drive. We live in the country so it wasn't easy but I came up with a surprisingly long list! Library story times, playgroups, toddler-only swims, museum craft time, that sort of thing. I've made a weekly schedule that I can refer to at a glance if we wake up, see crappy weather and still just need to get out. Another hit especially if I need a consumer fix is Ikea. It tends to be pretty kids-running-crazy friendly. And the best thing I've discovered lately is a farm museum with lots of indoor barn activities so it doesn't matter if it's raining when we go.
If we would prefer not to get in the car, cooking is awesome. Rainy days are perfect for trying out more complex recipes that require time. My DS will gladly taste test the afternoon away with me as he stands at the counter on his step stool. I also keep old boxes to open up for giant colouring projects.
Generally, I can turn just about any boring adult chore into a toddler game so I usually take advantage of a rainy day to do something lame like clean out the pantry - DS can make tin can pyramids as I wipe down the shelves. This afternoon we're going to be rearranging the furniture in his room. Sounds boring but I'm sure we'll find some long lost toys behind the bed and that'll make him very happy for a good chunk of time, and he'll be very happy to help push stuff around. Brushing the dog is also a good "chore" that can be made fun.
Happy mumma to my boys Henny Tom (Nov 30, 2008), Arlo Odie (Oct 5, 2010), and baby SISTER! due mid-Dec 2014.