Aside from Princeton's version, here's some starter questions (just answer the majority of the questions):
Why do you want to attend graduate school?
What research experiences have you had?
What are some topics that you think you might want to research?
What's special, unique, distinctive, and/or impression about you or your life story?
What details of your personal life or family problems (history, people, or events that have shaped you or influenced your goals) might help the committee better understand you or help set you apart from other applicants?
What are your career goals?
What is your ideal vision of the future?
When did you become interested in this field and what have you learned about it that further stimulated your interest and reinforced your conviction that you are well suited to this field? What insights have you gained?
Are there any gaps or discrepancies in your academic record that you should explain?
What skills do you possess? (i.e., leadership, communication, analytical)
If you worked during your college years, what have you learned and how has that work contributed to your growth?