I thnk Wes is right on target with his suggestions! Reading a good book was going to be my number-one recommendation, too, followed by writing one (your autobiography is a great place to start).
- Get online and teach yourself something new -- origami, self-hypnosis, sign language, capitals of the world, theoretical physics, nautical knots, the workings of the internal combustion engine...
- Close your eyes, open a kitchen cabinet, and grab three things without looking. Make something edible out of them.
- Search the internet for the names of people you remember from childhood... it's amazing how many of them you'll be able to find, and where they'll turn up.
- Design your dream house! Use graph paper if you have it, or a graphics program on your computer. Lay out the floorplan, furnish it, landscape it, draw cars in the garage. Design everything right down to the fabric on the chairs! It's great fun.
- See how much of your family tree you can draw from memory. Call your parents to fill in the blanks -- they'll be thrilled you asked!
- Dim the lights, crank up Elton John's "11-17-70" live album, imagine you're in a jampacked little underground club on that long-ago date, and dance your heart out in the middle of the living room floor. (Best cut: "Take Me To The Pilot.")