Evernote Peek is the newest edition to Evernote's lineup (Skitch is also very cool) and it is a very handy app for students. Essentially the app turns your notebooks into flash cards in conjunction with the smart cover (they have since introduced a way to use it without the smart cover). Simple to use, you create a note with a question for the title and the body is the answer to that question. You can then study using that notebook on your iPad. Genius.
If your students are using iPads in the classroom then I'm sure they have Evernote installed. This would be a great addition to that app and would allow students to create their cards right in class. If you aren't lucky enough to have a class set then you can share this app with your students and show them how to use it.