Evernote lets you clip web articles, capture handwritten notes, and snap photos to keep the physical and digital details of your projects with you at all times which you can then present at slides.
FocusTime helps you manage your efforts to concentrate and lets you track your progress.
iStudiez is a time management tool that combines tracking schedule, homework, and grades
iAnnotate lets you sync PDF, word, images, and PowerPoint slides and lets you use the pencil, highlighter, underline, note, and stamp tools to annotate your documents.
Quizlet lets you create flashcards and tests, and you can track your study progress and compete with your friends.
Khan Academy offers online learning modules for hundreds of different subjects at all different levels.