I am a general surgery resident and my time is very limited, but this app is great for getting some studying in while waiting for a case to start or between patients during clinic. I have two suggestions for features that I think would make it much more useful to me:

1) Custom lessons: I think something like this has been suggested by others, but here is my take on it. It would be great if on both Mac and iOS there was an option to create custom lessons. On iOS, the user would select "Create Custom Lesson" and then have a menu very similar to creating a custom playlist in the Music app. They could select entire cases, entire stacks, and individual cards all to be added to the custom lesson. On Mac, it would be even simpler. The user would "Create Custom Lesson" and then just drag and drop cases, stacks, and cards into the lesson. Just like a playlist in iTunes. This would be really useful because I have my cases and stacks very organized by subject and then sub-divided within those cases. Sometimes I may want to study anti-rejection drugs and chemo drugs in the same lesson, but they are in different stacks in different cases. I know that on the Mac I can create another stack and copy and paste the cards I want but this can be a bit tedious when pulling from lots of different places and there is no such option on iOS (of which I am aware).

2) I know this has been submitted by others, but just to reiterate: iCloud syncing. It would be so much better if my Mac, iPad, and iPhone could all just sync through iCloud (or Dropbox, etc) automatically so that I never have to manually update between my iPhone and Mac and iPad and Mac just to keep the most current cards on all my devices.

I sincerely hope that you can add these features in the near future.