I think it would be a great idea if there was a thread compiling the various server security plug-ins that are out there. Because I've been looking around and can't seem to find the threads for the plug-ins. Not talking about anticheating protection, there's SMAC for that. I'm talking about people trying to DDOS your server or trying to get administrator privileges and the like.
What's a good starting place at least for someone to look if they want to add some protection to their server?