Spring and summer have their fair share of rainy days (at least in Washinbgton, DC).  So it only makes sense to plan for the inevitable.

• For rainy weekend days, it's not a bad idea to keep a list of indoor chores you can tackle.  A rainy day is a great day to clean out a drawer or cabinet or closet.
• Keep a basic stock in your craft area so that you don't have to go out in the rain to work on your latest projet.
• I always like to have a few DVDs or a good book or a few magazines handy to read away a rainy day.
• Perfect a few rainy day recipes that take a little longer to cook.
• If you general workout outside (running, etc.), make sure you have an indoor alternative.