Labels is a qualitative text analysis system that I've written. It's simple - a set of Python scripts used to process documents marked up using XML. Though it is certainly not perfect, Labels is usable - I've have been using it myself quite effectively in recent months.
A warning. Labels has known bugs, and I can't make guarantees about its performance. Nevertheless, if you'd like to try it, please do. It is hosted on Launchpad: https://launchpad.net/labels/