A great observation is that having access to the content provided by Wikipedia is a delight in and of itself. That's a fantastic starting point for investigating, then, how you can enhance that experience with great design.
These guys did that with this brief. It's not the right answer, but it does raise some interesting questions. How do you design a more delightful Wikipedia without damaging the content? Because surely you agree that certain elements of Wikipedia - like editing pages, for instance - could use a good bit of delight here and there.