I agree. I am happy to have the problem. I am thinking of some sort of "Flashcard-Rank" that rates the quality of the card sets by using metrics such as number

I agree. I am happy to have the problem. I am thinking of some sort of "Flashcard-Rank" that rates the quality of the card sets by using metrics such as number of times studied, number of users who have saved the set, more than X number of cards and maybe a simple user rating system. The "featured card set" on the home page was a start of the "Featured Sets" idea. That was ok when there were less sets to choose from. But, yes, it is time to expand it now. Good examples and how-tos can really help. Thanks very much for sharing your thoughts.