We all know how hard it is to find out how popular your modules are, given how many CPAN mirrors there are, most of which aren't "official". For instance, the ISP that hosts my web and mail server has its own internal CPAN mirror which their subscribers are encouraged to use, as this cuts down on their external bandwidth usage. That mirror is, of course, completely invisible to everyone else.
Some people have tried to measure popularity by having their modules phone home during the test/install phase, but people don't like that and anyway, their stats will be skewed by the CPAN testing crowd who test/install their modules but don't necessarily use them.
I would imagine, however, that receiving bug reports and patches from users is a pretty good indicator of a module being popular. It means that people like your code enough to do your work for you and hunt down bugs.
So, in increasing order of popularity, my modules are