It’s a little cheezy but the following video has some applications for students that can be used on an iPhone or an iPad (or an iPod Touch).
Here are the references referred to in the video:
Coursesmart – Textbook eReader (http://www.coursesmart.com/iphone)
iStudiez Pro – Student Planner (http://www.istudentpro.com)
Cram – Study Tool w/Flashcards & Tests (http://www.cramapp.com)
Articles – Wikipedia (http://www.sophiestication.com/articles/)
Grades – Grade Course Calculator (http://www.gradesapp.com)