Right. So instead, try this:

my %data = (
      'slashdot.org' => 180,
      'cpan.org'     => 150,
      'perl.com'     => 150,
      'apache.org'   => 120,
  );
my @keys = keys %data;

# invert the %data hash, creating arrayrefs each with list
# of elements with the same ranking
my %ranks;
push @{$ranks{$data{$_}}}, $_ for @keys;

# count/sort the rankings
my @ranks = reverse sort {$a<=>$b} keys %ranks;

for my $rank ( 0 .. $#ranks ) {  # print them
  my @tied = @{$ranks{ $ranks[$rank] }};
  if (@tied > 1) {  # more than one with this ranking
    local $"=', ';
    my $last = pop @tied;
    print "@tied and $last all have rank ". 1+$ranks[$rank] ."\n";
  } else {
    print "@tied has rank ". 1+$ranks[$rank] ."\n";
  }
}
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Update: Rankings should be 1-based.

dmm