And now for my attempt to reinvent this wheel:

my @alpha = ('a'..'c');
my @counter = ();

sub get_next {
  for (@counter) { 
    $_++;
    last if ($_ <= $#alpha);
    $_ = 0;
  }
  push @counter,0 unless grep($_>0,@counter);
  return join"",map($alpha[$_],@counter);
}

for ($_ = get_next();4 > @counter ;$_ = get_next()) {
  print "$_ ";
}
__DATA__
output: a b c aa ba ca ab bb cb ac bc cc aaa baa caa aba bba cba aca b
+ca cca aab bab cab abb bbb cbb acb bcb ccb aac bac cac abc bbc cbc ac
+c bcc ccc
[download]

Of course, maybe it was a silly try. But still, I like it :)

Hope this helps.

antirice    
The first rule of Perl club is - use Perl
The ith rule of Perl club is - follow rule i - 1 for i > 1