While metrics never give the whole picture, they sure help ask interesting questions. For instance, I hooked up CVSMonitor to the repository for my current project, and this was the result:
On the face of it, I've taken away as much code as I've added, leaving David to do all the work. We kicked around a few other hypotheses as well, but overall it reflects the fact that I've worked on some difficult components - like the printing subsystem, which I had five goes at before I hit on a combination of technologies that works reliably.
CVSMonitor has plenty of other tricks too, including finding changesets and allocating blame.