WolframAlpha This app still blows my mind. Enter a recipe and it will break down every calorie and vitamin. Enter ANYTHING and it will break it down mathematically. Like Google for the math-minded.

World Atlas by National Geographic This atlas is easy to use and impressive.

Dictionary for iPad This is a no-brainer. When you're doing all that reading, you need to have a way to look up all the new words you're using, right?

NYTimes for iPad I am a huge fan of the New York Times and the clean design and easy use of this app makes me insanely happy.

Wikipanion for iPad This app is smooth, easy to use and (dare I say it!) better than the original Wikipedia.