PHP Code:
if (!defined('IN_SCRIPT'))
{
header("HTTP/1.0 404 Not Found");
exit;
}
This kind of code is old (PHP4 era) and should be avoided. When using OOP properly, the script will not be ran, so you should be using OOP properly 
PHP Code:
$tor_exit_node_list = '<?die;?>' . "\n" . '<!' . date('G') . '!>' . "\n" . $tor_exit_node_list;
When I first saw this code, my syntax highlighter displayed it wrong, taking the ?> as a closing tag, not part of the string. You could have an issue with this, I could recommend splitting it up like so:
PHP Code:
$tor_exit_node_list = '<?die;?'.'>' . "\n" . '<!' . date('G') . '!>' . "\n" . $tor_exit_node_list;
Function parseCleanValue can be replaced with htmspecialchars.
You should never use @ to suppress errors, as it is slow. You should never use globals - perhaps experiment with the Singleton pattern for the database class.
How about cleaning out register_globals?
You're releasing it under GPLv3, meaning that anyone who downloads can do whatever they want to do with it, as long as they release it under GPLv3 themselves. Therefore "DO NOT REMOVE THE COPYRIGHT, I WILL TAKE LEGAL ACTION" violates the license.
Moving to the appropriate forum, too.
It looks like a pretty good script!