1. Travel to Italy and stuff myself with food, wine and beauty.
2. Give away my possessions in person to people who would like them. Much more satisfying than writing out a will.
3. Wear a velvet smoking jacket and an ascot ALL THE TIME and try to be the world's smoothest lothario.
4. Publicize my plight and try to garner public support for a free trip into space. Yes, I know this will never happen, but I'd have to try.
5. Write a book that's partly a memoir, partly a confessional, partly a chronicle of what it's like to slowly die fully cognizant of your fate, partly a love letter to people in my life, and partly a collection of life lessons for my nephew. All while being funny instead of mordant. This would be the most important thing I could do, and I've never seen a book quite like it.