I found it very useful to "dictate" my review books and then listen to them after at a faster rate on the second and third pass (very helpful for boards).
There is a great app called "dictamus" that turns the iphone into a stellar dictaphone. There is even a free version with limited functionality to see if it'll work for you, full veresion costs $10.
I like the ReachMD app for audio learning. And there are tons of great podcasts out there.
You can make "flash cards" on powerpoint, store on "dropbox" and review that easily anywhere - plus you can easily share powerpoint files and get your friends to make them as well and share amongst your study group.
The best app to use for flashcards would probably be "anki" which can be used in safari or you can buy the app (it's pricey though). You can also share these files and use them on iphone, ipad, or pc/mac.
There are also programs that allow you to convert text to speech (google this). I had a question bank in PDF that I converted and this helped me study for step 3 during my commute for intern year. Since the format was question, answer choices, answer explanation it was an excellent way to review in the car.
