1. Currently just strips all trailing white space
2. If passed a reference, operate on it directly (duh! But also works for passing arrays of references) and return a dud value
3. Otherwise return the modified string(s) without touching the originals.
4. Works on scalar, arrays and hashes (why not? :) It modifes the values, not the keys, though it would be no problem to add that, too)
5. Recursive (didn't a just read something here about "real" uses of recursion?) so you can use wacky data structures.

I didn't put a lot of brainpower into this; just wanted to share a thought of improvement. Enjoy!

sub mchomp { 
  my @a=@_; 
  local $_; 
 
  foreach (@a) { 
    if (ref $_ eq 'SCALAR') { 
      $$_=~s/\s+$//; 
    } 
    elsif (ref $_ eq 'ARRAY') { 
      @$_=mchomp(@$_); 
    } 
    elsif (ref $_ eq 'HASH') { 
      for my $k (keys %$_) { 
        $_->{$k}=mchomp($_->{$k}); 
      } 
    } 
    else { 
      s/\s+$//; 
    } 
  } 
  wantarray ? @a: $a[0]; 
}
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Examples

  ## returns the modified string
  print mchomp $string;
  ## modifies the variable directly
  mchomp \$string; print $string;
  ## returns an array of modified strings
  print join ",",mchomp @array;
  ## modifes the array inplace
  mchomp \@array; print join ",",@array;
  ## returns the modified hash
  %new=mchomp %hash;print values %new;
  ## modifes the hash inplace
  mchomp \%hash;print values %hash;
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