Until recently, I worked for the Idaho Commission for Libraries as a web developer engaged with a number of projects based on Drupal and a few custom coded apps. It was a job I held for about eight years, starting as a part time grant funded assistant to the library networking consultant. As my skills increased, the agency's needs grew, and the Internet germinated, and it became a full-blown web designer and state employee position. A few years later I was reclassified as a developer.
Sometimes you want to measure how much you've contributed to Drupal.
Sometimes you want to measure someone else - perhaps you're considering hiring this person.
Try the following Google search (where "username" is the person's Drupal.org username):
That's it. Not scientific or anything, but it'll let you get a handle on how often a person's username appears on http://cvs.drupal.org.