What I'm seeing here are not alternate alignment systems, but different ways of keeping track of standard alignment. Interesting and useful, but not really what was asked for.
So I now present a system first presented in the Dangerous Journeys: Mythus rules.
Here there are five alignments, each known as an Ethos. While they range from mostly good to mostly evil, each is not exclusively good or evil, ordered or disordered. While the Ethos of Sunlight is mostly benign, there can still be creatures of fell nature found within, for even sunlight can blight and destroy. Whereas the Ethos of Gloomy Darkness can provide a blanket of cooling darkness, and allow for restful, healing sleep.
The five Ethoi are:
Sunlight: Life, healing, aid for others. Also the withering light of the harsh midday sun. Without it nothing could grow. But too much means death.
Moonlight: Nature, growing things. Also the darkness of the deep forest, the wolf bringing down the calf. This is the ethos of the farmer and the druid, both people closely tied to the land and the cycles and rhythms there of.
Balance: Pretty self explanatory. A militant Ethos dedicated to ensuring that no one has an undue advantage over another.
Shadowy Darkness: The Ethos of trickery, deceit, and cunning. The Ethos of cleverness and resourcefulness. It is the ethos followed by those who would gull the naive into thoughtless deeds, and the ethos of those who would strike against tyrants when those tyrants have the advantage.
Gloomy Darkness: Death, despair. The cool of the night after a harsh, burning day. It can hide the foul from those who would destroy it. It can hide the fair from those who would destroy it.
Each has its general tendencies. Each also has ways in which it belies, even contradicts the popular image. A follower of Shadowy Darkness can be honest, one of Sunlight cruel. But the general tendency is to follow the herd.
So there you have an alternate alignment system.