I think the Tutorials already serve well as a nascent rating/tagging service for perl modules. If a person is so keen on a module that they are motivated to write a tutorial for it, that is a strong endorsement for the module as well as a nice tutorial.

Since PMdev also keeps the tuts nicely organized, I also think that section serves as sort of a reverse tagging service: you tell me the topic you are interested in and I will tell you some fine modules to look into.

Perhaps a direct rating service (along with possibility of comments) would be a nice addition to Perlmonks. It could be arranged as daily or weekly poll:

File::Find -- sucks or rocks?