Finding a Module on CPAN/Module-Rank
The CPAN Module-Rank aims to be an automatically calculated metric for CPAN modules similar in purpose, but not in implementation to Google's PageRank. When we say it's automatically calculated it does not mean the data it is based on was not generated by humans. Even Google relies on the mostly human-generated web to build its index, but like Google's search results the Module-Rank calculation for a given query will not require human intervention.
Parameters for Discussion
Last update date
Not fully indicative, but still a useful parameter.
Average activity over time. (How many releases and how frequently)
CPANTS Kwalitee Score
Or specific metrics.
This is hard to determine. Sometimes a program break due to the assumptions of the development system. (Such as only Linux or only Mac OS X).
Number of incoming references/dependecies in (WWW, CPAN, etc.)
Total number of reported bugs (both open and closed)
The more bugs people have reported for a module, the it is indicative that people are using it. We shouldn't judge based on open bugs alone, because that will encourage people to keep them open.