my %month = (
   "March 2005" => "0305",
   "April 2005" => "0405",
   "May 2005" => "0505",
   "June 2005" => "0605",
   "July 2005" => "0705",
);

print option_list(\%month);

sub option_list {
    my $options = shift;
  return
    "<select>\n" .
    (join '', map{ qq!<option value="$options->{$_}">$_</option>\n! }
    keys %$options ) .
    "</select>\n";
}