How about hierarchical data? E.g., a country's laws / statutes? Thousands of text files organized in a hierachy. I've resorted to relational denormalizing and hacks to get decent performance. So I'm wondering if a graph database would be a better fit.

E.g., I frequently need to query, "What is the list of ancestors from the object to the top of the tree?"

In a relational system, this needs to be stored in some kind of data structure, which is redundant. But theoretically in a graph database, it'd be a fast O(log n) query if I'm not mistaken.