Nifty Challenges from Stanford pages.

If you are looking to test your knowledge of different data structures, I recommend checking out Prof. Nick Parlante's Stanford pages, where he has, what he calls a Nifty assignment archive.

Nifty Challenges

The thing you have to like about these assignments is, these are practical, real-world problems. for e.g., "catching Plagiarism in a given set of documents". The target for this solution could easily be a book publishing house that wants to use your progam.

If nothing else, it helps think about the different data structures that you can apply to the problems to resolve them.