visualizing B-tree index coverage

Does anyone know of a tools that allows one to visualize
the tree created by a multi-column B-tree index?
A picture of a tree with branches, showing how "branchy" the
tree is would be great.
I'm wondering how well I've "clustered" the data in my table
using the multi-column index. In other words, do my
multi-columns sufficiently but not overly discriminate rows from each other?
Do I have too many with the same index? (not enough branches)
Do I have a unique index for each row? (way too many branches)

Thanks,
TJ