i wasnt too sure about why you obtained the @dirs, but other than that this seems to work pretty well.
(I would also look into replacing grep...)

opendir(DIR, $directory) || die print "Couldn't open directory";
my @unscont = readdir(DIR);
closedir(DIR);

##  Sorts and Extracts in one statement(each)
my @files = sort grep(/\./, @unscont);
my @dirs = sort grep(!/\./, @unscont);  

##  Removes 1st two elements '.' & '..'
@files = @files[2..$#files];

my @noshow = (".py", ".html");

foreach $f (@files) {
  my $switch = true;
  foreach $n (@noshow) {
    if($f =~ /$n$/) { $switch = ''; }
  }
  if($switch) {
    print "  <a href=\"./this?func=read&file=$f&dire=$dire\">$f</a><br
+>\n";
  }
}
[download]