As I mentioned in the Live Support thread, Help Center live (helpcenterlive.com) is an amazing script that uses PHP and MySQL. It can do trouble tickets, FAQ, live chat, and other things. I find it to be very useful. You get emails when new tickets are created and responded too. Also, users register when they create a ticket, and they must provide information such as name and email address which may be good to have if you need to contact them for some reason. And best of all, its FREE!