Isn't Orcus the leader of 'madmen' ??
Thankfully, D&D dropped the idea that Chaotic Neutral = insane.
A Chaotic Neutral individual is a "free spirit". They have no regard that a person, government or being* has power over them or that they have responsibility to. They don't perform an act because they have particularly strong opinion whether it is right or wrong, good or evil - they act in a manner based on their emotional reaction (or what some might refer to as "whim"), or a very careful, if convoluted reasoning (though not necessarily logical). A Chaotic Neutral might be cruel (in a "Some people just want to watch the world burn" sort of manner), but more often they will act in a way that doesn't bring negative repercussions to themselves. Their approach towards others could probably be summed up as "Disturbeth not the leaf, lest the tree fall on your head." If a Chaotic Neutral individual takes a disliking to someone, they generally won't bother to hide their disdain, unless they don't feel they are in a position to act without harmful consequences to themselves.
Individuals whom I consider to be generally Chaotic Neutral:
Lando Calrissian, Jar Jar Binks (Star Wars)
Dave Lister, Cat (Red Dwarf)
Harry Mudd, Q, Quark (Star Trek)
Lawful Neutral is, of course, the opposite. Everything has its place in the order of the universe. Nothing happens without reason or intent. They expect others to "know their place" in the pecking order of the universe and may become upset at those who flagrantly flaunt the law or abuse a legal system. Often, if they can't define it and put it into a category, it doesn't exist. Woe betide those who attempt to change the status quo in their presence - things are the way they are for reasons; even if such reasons aren't understood, whoever put those rules in place knew what they were doing and wouldn't have done so without a good reason. Lawful Neutrals aren't outright evil, and in many cases are excellent at being good citizens doing good works within the confines of the law, but they can quickly fall afoul of blindly following misanthropic rules or leaders without question - possibly even rationalize such acts as "in societies best interests". If a Lawful Neutral individual takes a disliking to someone, they will only handle the situation if they are authorized to do so, otherwise they will report the individual to a superior (along with a detailed list of grievances) to sort out the situation. Furthermore, if the superior fails to act, they rarely will take matters into their own hands, though they may continue to prod their superiors until they act or are commanded to cease being a bother.
Individuals whom I consider to be generally Lawful Neutral:
C-3PO, Admiral Piett (Star Wars)
Arnold Judas Rimmer, Kryten (Red Dwarf)
Spock, Odo (Star Trek)
* A chaotic neutral person is not necessarily an aethist, but is unlikely to have a strong faith in any power other themselves ("Hokey religions and ancient weapons are no match for a laser blaster"). When worshipping a deity, it is more often an act to curry favor should a time of need arise, keep away a god's wrath or simply a habit from being raised in an environment where it is expected - though in the latter case the chaotic neutral probably doesn't pay much mind whether the deity actually cares about their well-being and is just paying lip service.