While this post is directed more towards native iPad app development, many of the suggestions are also applicable to any sort of app or web development. I especially liked the part on minimizing user input based on what you already know about the user. That’s a topic we covered at length in my mobile web design course.
No one wants to spend a lot of time setting up a $1.99 app. Leverage as much of what the iPad and other websites know about your users as possible (with their permission, of course). Could you use the user’s location, calendar, Twitter feed or contacts list to make the app smarter and more personalized?