Thanks for the comments. I do realize that some of these metrics are of the "for what it's worth" type. That's why I chose to be completely transparent with how they were obtained. And part of my posting on Perlmonks was to figure out how to improve them.

Some of the problem is how to get at certain metrics. Some you just obviously can't get (e.g. how many companies in America use Perl for internal web development?) in any reliable way, and definitely not with my limited resources. The metrics I currently have are web scrapings, which are relatively easy to obtain, but have their problems, like reliability, granularity, etc.

Some metrics may be obtainable, but would require much greater effort. For instance, I thought it would be interesting to see for various languages how sizable, active, etc their module repositories were. But at this point I haven't even started to delve into figuring out how to go about getting this data.

I do like your suggestions, and I'll take them under consideration. As for "instances of use of finished -- eg. well debugged -- programs", I think a SourceForge top N (I was thinking 100, but perhaps more) metric is sort of along these lines.