Try something like this:

use strict;
use warnings;
use CGI::Pretty qw(:standard);

print header,
    start_html(
        -title  => 'CGI.pm and Javascript',
        -script => {
            -language => 'JAVASCRIPT',
            -code     => q|
                function launch(select) {
                    if (!select.value)
                        return false;
                    window.location.href = select.value;
                    return false;
                }
            |,
        },
    ),
    start_form,
    popup_menu(
        -name     => 'jump_box',
        -onChange => 'launch(this)',
        -values   => [qw(
            http://google.com
            http://perlmonks.com
            http://imdb.com
        )],
    ),
    end_form,
    end_html,
;
[download]

UPDATE: sigh ... it's just an example dorward. Personally, i see nothing wrong with using Javascript for such means, even though some people don't use Javascript or use only their keyboards. The OP asked for drop down menus with Javascript. This is an application of such. Personally, i would much rather use HTML::Template or Template Toolkit than CGI.pm ... but this is a working example of how to do it with CGI.pm.

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)