In the spirit of TIMTOWTDI, this example uses hash lookup which may be a bit more efficient than grep (provided that %noshow is small and @files is medium to large. The larger, the better.):

use strict;
use File::Basename qw( basename );
print "Content-type: text/html\n\n";

opendir(DIR,"./") or die "Couldn't open directory";
my @files = readdir(DIR);
closedir(DIR);

my %noshow = ("." => 1,
              ".." => 1,
              basename($0) => 1
);

foreach my $f (@files) {
   print "$f<br>\n" unless exists $noshow{$f};
}
[download]

--Jim

Update 1: I used the example by Chmrr as a starting point.
Update 2: Added File::Basename support. Thanks tye.