Here's my most commonly used apps. Hopefully you'll find some useful as well. I tried to list all the free apps i use, but many of these have paid versions as well if you were interested. (I personally use mostly the free versions).
($0.99) - I use this app every day. Keeps classes and assignments organized.
(Free) - this is like Google drive. No need to carry around usb drives since everything is stored in the cloud. You can access your documents anywhere and has built-in MS Office to view PowerPoints, work on word docs, and so on.
(Free) - This is my main workhorse. I use this to take notes and insert pictures of the material I'm studying. Each of my courses has its own "notebook" where everything is broken down by chapter.
(Free) - Build your own flashcards or download an existing deck created by other users. Put in a question on one side and tap the card to flip it over to see the answer. You can also use pictures.
(Free) - keeps you up to date on the newest App Store apps, sales and freebies
(Free) - Huge directory of clinical reference material.
(Free) - Another huge database for almost anything medical related you can think of for a clinical setting
(Free) - News and medical abbreviations.
SoundBuiler by Littmann
(Free) - a learning tool designed to help improve the auscultation skills of students and practicing clinicians. I highly recommend this one as well.
3D Cell Lite
(Free) - 3D tools and simulations for Cells.
(Free) - 3D molecules
(Free) - Lessons about the periodic table
(Free) - Lets you learn, play, discover and explore the chemical elements at the atomic scale.
Periodic Table Lite
(Free) - Nice interactive and informative periodic table.
3d musculoskeletal quiz
(Free) - quiz on the musculoskeletal system
Skeletal Head & Neck Pro III
(Free) - A great app to study the head and neck bone structures.
(Free) - 29 interactive structures. Discover how each brain region functions, what happens when it is injured, and how it is involved in mental illness.
Visual Anatomy Lite
(Free) - Interactive anatomy reference with Gray's anatomy images add-on, a muscle highlighting tool and full description.
Edit: I use these on my iPad, but many, if not all, should work on your iPhone.