open RESULTS, "> $results_file"
                or die "Failed to open $results_file for writing\n";
print RESULTS join("\n", @results);
close RESULTS;
[download]

That's missing the final newline (a common mistake). Perhaps you wanted:

open RESULTS, ">$results_file" or die;
print RESULTS "$_\n" for @results;
close RESULTS;
[download]

And as for:

  $access{$_}{old} ||= 0;               # defaults to avoid warnings
  $access{$_}{new} ||= 0;
  if ($access{$_}{old} > $access{$_}{new}) {
        push @results, "$_";            # keep results rather than pri
+nting
  }
[download]

I'd recast that as:

  if (($access{$_}{old} || 0) > ($access{$_}{new} || 0)) {
        push @results, "$_";            # keep results rather than pri
+nting
  }
[download]

mostly because I hate changing values when all I'm really trying to do is test them. One of the many reasons why I'm not religious about enabling -w.

-- Randal L. Schwartz, Perl hacker