I am also a frequent user of Anki. The only problem I see is that its preferences (intervals, set length, etc) are at the first glance not that easy to figure o

I am also a frequent user of Anki. The only problem I see is that its preferences (intervals, set length, etc) are at the first glance not that easy to figure out. Besides simplifying it a bit more, I see very little options to improve the standard Flashcard system. Plus what makes Anki awesome is the ability to use the cards on every OS, making it a ideal collaborative tool. But as mentioned by tom_b you need to create your own decks. There is very little use for most public decks unless you have the extreme lucky moment having to learn exactly the same as the author of the deck did. In fact this might be a more interesting place for innovation - the management of Anki cards. Not sure how the market situation looks but you could be offering cards for popular textbooks or create a marketplace for these in order to rise the quality. Not sure how the copyright situation looks like, but you could be entering also a more mainstream market - for example by offering a card deck for each issue of Mental Floss in order to learn at least a few interesting things each month.