One of the older sites that is pretty extensive is this one:
The Alignment System
However, I really like the exploration of how to play various alignments in a realistic way here:
Alignment - Pathfinder_OGC
I mentioned my current character ended up drifting in Neutral Evil, but I play her as a paragon of "pragmatism," with a dallop of narcissism thrown in for good measure. I usually don't play "evil" and I didn't want to do something cliche -- my whole goal was to present her in a way that others could mistake her for "good" until they really understood her motivations. So she'll do good things if necessary but generally for selfish reasons at core, and she could sell others out if it suits her enough. She also can justify all of her actions with some rational-sounding reason, to support the end-goal. She doesn't even really recognize she is evil, at this point; she still thinks she's a good person. She has had others call her an evil person, and she just dismisses it as absurd.
Ledger's "Joker" is probably Chaotic Neutral. Dr. Doom leans towards a more lawful/structured type of Evil. Captain America and Superman are typically viewed as Lawful Good. And so forth.The idea of lawful evil or rule abiding evil and chaotic or lawless good are totally intriguing ideas. I'm already trying to figure out what marvel or DC characters I would consider in each category.
Batman's interesting... he operates outside the law. We think he's generally "good" but maybe not good to the degree Superman is, and he might even veer into Neutral in later representatives of him. He's focused on justice, but it almost becomes revenge.