me gusta~ :3 we must always strive for the usefulness of good

Now THAT is a good idea! That may serve as a backstory for a character I create at some point. :3

what happens when a neutral person wears it?

Then it pushes them into an alignment extreme. Personally I'd say that whatever their natural tendencies are strongest in, it reverses them and enhances the result.

Example: Lawful neutral druid, generally sticks to his grove and discourages visitor, though generally without violence unless necessary.

Enter helm, he becomes Chaotic Evil, and leaves his grove actively persecute the decadent city folk. He would probably lose some class abilities for not having a neutral alignment but he'd figure something out.

Ah, cursed items. perhaps the site should branch out into that. :) this one is still not as fun as the Belt of Gender Swapping. :P

If I had this I'd so turn a gnoll to be my best buddy