Recently we've had some students asking about flashcard apps. Here are some suggestions (all for iPhone/iPad unless noted).
Make your own:
Flashcards Deluxe ($3.99)
Includes pictures and sounds, zoom into pictures, and auto-repeat sounds.
gFlashPro - Flashcards & tests ($3.99)
Has ability to include zoomable images and audio/video clips directly through gFlash editor.
Add audio and image to any card side.
Modality learning/epocrates ($24.99 & up)
Various flash card apps based on medical textbooks (including Netter's).
For reviews of medical apps, check out Imedicalapps.
Looking for more apps? Here's a curated list from medical students at the University of Minnesota: http://www.meded.umn.edu/students/ipad_apps.php.