Assuming you mean sorting normally:

sub beautify
{
    my %stuff;
    @stuff{@_} = undef;
    return sort keys %stuff;
}
[download]

so that:

print join ' ',beautify(qw(h e l l o w o r l d)); # prints "d e h l o 
+r w"
print join ' ',beautify(qw(b u m b l e b e e));   # prints "b e l m u"
[download]

If you want it sorted by frequency increasing:

sub beautify
{
    my %stuff;
    $stuff{$_}++ for(@_);
    return sort { $stuff{$a} <=> $stuff{$b} } keys %stuff;
}
[download]

so that:

print join ' ',beautify(qw(h e l l o w o r l d)); # prints "e w r h d 
+o l"
print join ' ',beautify(qw(b u m b l e b e e));   # prints "m u l e b"
[download]

You can, of course, reverse the result if you want it highest-frequency-first.

Hope this helps.

Update: Rrgh -- someone else always posts first while I'm typing my reply...