App-Related Websites. Then check out the list of apps for Reading &Writing, Math & Science, and Communication & Visual Supports.
Of course, these lists aren't comprehensive, but a great place to start. Remember, there's even apps to help you find other, related apps. Check out Discovr for suggestions of apps similar to ones you like.
When you've had success with apps in education, please share your knowledge at Teacher Recommended iOS apps, a new project of MITS that seeks to match specific apps to learner challenges and content area. Thanks to MITS and Peter Schaafsma for great iPad presentations.