AnnoCPAN is a web interface for the documentation of all the modules
on CPAN, where users can add annotations on the margin of specific
paragraphs throughout the POD. The master AnnoCPAN site is located
at http://annocpan.org/.

The Perl 5 module AnnoCPAN::Perldoc provides a substitute for the
'perldoc' command that displays the annotations locally and without
requiring a connection to the Internet. It works by using a local
note database that can be downloaded from http://annocpan.org/annopod.db