TreeLike is an experimental tool providing a quick way to understand the shape of multi-dimensional data in a tabular CSV or JSON file.
Demo (you'll need a data file, how about: MySQL world data)
It immediately shows the distributions of values in all columns, and by laying out the columns in some nesting order, can show hierarchical relationships between values across columns. When two columns have a many-to-many relationship, the merge feature shows connections in both directions, not just from parent to child. And parent/child relationships can be reordered with one or two mouse clicks.
TreeLike will be most helpful with files of between about 4 and 20 columns. It should be fine with at least tens of thousands of rows, but it hasn't been well tested.