Mine

#!/usr/bin/perl

use CGI qw(:standard);
use Net::Ping;

$host = param("host");

$p = Net::Ping->new();
if ($p->ping($host)) { $color = "80FF80"; }
else { $color = "FF8080"; }
$p->close();

print "Content-type: text/html\n\n<HTML><HEAD><STYLE TYPE=\"text/css\">BODY { background-color: $color; }</STYLE></HEAD><BODY></BODY></HTML>";