I always thought evil was based on
'how do you value the life of other sentients'...
..so humans in this world, one of many races in the fantasy world
so the sum of things like
slavery,
how you treat non-coms / civilians,
prisoners,
your own sick, eldery and infirm
other races
other sexes
others philosophy and religion
Some may try to enslave others, killing only trouble causers and those they view beneath being labelled 'human'. They will do this to further there own collective cause and ideals. If they have ill and eldery, they may care for them as they have wisdom, skills, tales, evidence of heritage / legitimacey to pass down, etc
So lawful evil empires and such
...more later...got to go
This is certainly one way to go, but I think that the borders between good and evil can be easily blurred in such extreme situations, because people will rationalize their choices. Example - how goblins, orcs and other "evil" races are treated by LG characters in fiction everywhere. On the other hand, there are situations where Lawful/neutral/chaotic trumphs over evil/good/neutral, and vice versa.
IE: instead of a fight, you decide to play a game of cards with X
Both lawful good and lawful evil, once they agree to do so, will honour both the agreement and letter of contract. The LE will try to make a sneaky paragraph, and LG will try to put only himself on the stake (on top of sneaky paragraphs, like "word of evil is no good anyway", see Teutons). True neutrals and LN will probably be close to this.
Neutral evil (and some chaotic good) will use marked cards, will cheat while dealing and hide aces, and on the off chance that they loose anyway - they will stab your ass.
There is a lot of use for simplified alignments, but it's important to remember there's more to that.
As a light literature on subject of acting evil, I reccomend Phil Zimbardo's "
The Lucifer Effect" (yes, it
is a light read, even if the book itself has a slight size penalty ;-). Zimbardo has a way with words, and his books are a great gateway into psychology). Note, that this book does not shed much (if any) light on what we'd call chaotic evil. Both ChEand NE would probably be better described as parts of psychopathy.
Um... I'm gonna shut up now. This (psychology) is a subject of interest for me, so I tend to babble a bit when poked.