my @sorted_keys =
  sort { extract( $hash{ $a } ) <=> extract( $hash{ $b } ) } keys %hash;

for my $key ( @sorted_keys ) {
  # whatever
}

##</code><code>##

my @sorted_keys =
  sort { $hash{ $a } cmp $hash{ $b } } keys %hash;

for my $key ( @sorted_keys ) {
  # whatever
}

##</code><code>##

my @sorted_keys =
  map  { $_->[0] }
  sort { $a->[1] cmp $b->[1] }
  map  { [ $_, extract( $hash{ $_ } ) ] }
  keys %hash;

##</code><code>##

my @sorted = sort { f($a) cmp f($b) } @unsorted;

##</code><code>##

my @sorted = sort { f($a) <=> f($b) } @unsorted;

##</code><code>##

sub f {
  my $key = shift;
  return $hash{ $key };
}