Msmouth, I was in the same boat as you when I was studying for the NBDE. I didn't want to carry around a ton of flash cards, I also don't like flipping to the back of the book. Seems like everything I did on the site was a response to what I wished I had access to while studying for my own tests and the frustrations with existing materials. I worked with a bunch of students who had just passed boards and created a bunch of questions for your board prep. To be honest with you, they aren't very popular -> though mostly because nobody knows about them. We are working with ASDA which gave us a positive review in a partnership to change that, but would really love more feedback on what you like and don't.
One thing I don't like about it is that some topics like "Dental Anatomy -> Teeth" has hundreds of questions, and it is hard to be sure you have taken all of them without doing them all at the same time, or repeating ones you have already seen. I hope to change that, but it won't be for a couple months.
I also realized a few weeks ago that there wasn't any free sections for people to check out what we have, which might have contributed to an awareness issue, I changed that so you should be able to take a peek and see if you like what you see.