My personal favorite, which a friend and I came up with after a reasonably long discussion, is that every human is True Neutral, with anyone who has a differing alignment gaining that alignment subtype.

Because, quite frankly, if you are going to separate things up, you better point out how alien someone who is say, Neutral Good.

They aren't a nice person; nothing says they have to be nice... sure, they make Mother Teresa look like a person who kicked puppies in front of crippled children while laughing, but they will probably be incapable of communicating with other beings.

And Lawful? Forget just having a personal code; a Lawful person would make someone with OCD look all loosie-goosie.

Another thing I'm working on is trying to port Intimacies over to DnD, just because they are far more definite than any alignment system. Eh, they'll end up being very similar to Allegiences, but oh well.