Aside from trying
perldoc
individually for any CPAN module that takes my fancy or going through the file system and loo
Here's a really hacky way to do it in *nix, you'll get some stuff you don't really care about (ie: warnings::register etc), but it should give you a list of every .pm file that's accessible via perl.
for my $path (@INC) {
my @list = `ls -R $path/**/*.pm`;
for (@list) {
s/$path\///g;
s/\//::/g;
s/\.pm$//g;
print;
}
}