I'm currently testing Transana, a free and open-source software for qualitative analysis, developed at the Wisconsin Center for Education Research.

Transana is software for professional researchers who want to analyze digital video or audio data. Transana lets you analyze and manage your data in very sophisticated ways. Transcribe it, identify analytically interesting clips, assign keywords to clips, arrange and rearrange clips, create complex collections of interrelated clips, explore relationships between applied keywords, and share your analysis with colleagues. The result is a new way to focus on your data, and a new way to manage large collections of video and audio files and clips.

Transana runs on Windows in both single-user and multi-user versions. A Macintosh version is in development.

The beta version for Mac OS X I am testing seems to be pretty good.