Compus is a visulization tool aimed at analyzing corpora or XML documents.
You can have a look a rich corpus of transcribed french manuscripts of 1530-1532, here.
You can download Compus 1.0 here and the compiled version here. Compus is distributed under the GNU Public Licence.
There is also a rudimentary Compus manual available in the distribution.
and Analysis of Structured Documents For Understanding Social Life in the
Jean-Daniel Fekete and Nicole Dufournaud, Proceedings of Digital Libraries 2000 (DL00). ACM. June 2000, pp 47-55.