Something you hope to do in your life.
I used to say get my PhD when asked this question....but the longer I am out of school the less I think that will actually happen, so I'm going to go another direction completely with this: I want to travel, like take-a-year-and-see-the-world-and-do-it-off-the-beaten-path-travel.
I did not come from money, but somehow my parents scraped together their pennies and sent me to Europe for two weeks when I was 15 years old. Both my siblings have also been (my sister to England and my brother to France) on similar trips, you know, the ones organized by language courses and in my sister's case, her civics class, during high school. I took German in high school, so off to Germany I went (we also visited the Czech Republic, Austria, and Hungary.) It was amazing, and all I have thought as I've gotten older is how much more amazing it would be as an adult. That trip opened my eyes to how big the world is and is a huge factor in why I chose to study Anthropology and Sociology in college. (Side note: When I was still single, I thought about joining the Peace Corps after getting my degree but then life happened, I had a reason to not live outside the U.S. and that didn't. C'est la vie.)
There is so much to see and do outside of this country, and I want to see and do those things. Someday, somehow it will happen, most likely in approximately 15 years, when both the girls will be of age and (hopefully) in college.
I should probably start saving my own pennies now....I don't want to think about how much a year of world wide travel will cost in 15 years.