$ find /usr/local/lib/perl5/5.8.1/ -name "*.pm" -or -name "*.pod" | \
xargs perl -lne 'print if s/^=head1 //'  | \
 perl -lne '$ndx{$_}++;END{for(sort{$ndx{$b}<=>$ndx{$a}}
 keys %ndx) {exit if$count++>30;print"$_ => $ndx{$_}"}}'