i'm not really sure what you mean, but here goes:

sub sortByValue {
  my %hash = @_;
  sort { $a->[1] cmp $b->[1] }
    map { [ $_, %hash{$_} ] } 
      keys %hash;
}

foreach $pair (sortByBalue %myHash) {
    print "$pair->[0] - $pair->[1]\n";
}
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or, if sortByValue should return only the keys:

sub sortByValue {
  my %hash = @_;
  sort { $hash{$a} cmp $hash{$b} } keys %hash;
}

foreach my $key (sortByValue %myHash) {
  print "$key - $myHash{$key}\n";
}
[download]

the fun thing to do would be to tie a hash table to return it's keys sorted based on the values for the each function. (i'd bet my left pinky this exists already on CPAN)