# Warning: untested!

use CGI;
use LWP::Simple;

$q = new CGI;
$date = $q -> param ('date');

$param1 = $q -> param ('param1');
$param2 = $q -> param ('param2');
# etc. The idea here is to load up whatever other 
# parameters you plan on getting from your script.

if ($date eq 'today') {
    $output = get ("http://www.foo.com/one_cgi?param1=$param1&param2=$param2");
} else {
    $output = get ("http://www.foo.com/two_cgi?param1=$param1&param2=$param2");
}

print $q->header;
print $output;