Is there an option to hide my character's helmet?

I'd really like to hide my helmet. I haven't found any in-game options, but maybe I missed it. Is there an option somewhere, or an INI file I can edit, to be able to do this?

No, there's no option to hide helmets.

If you really want that badly, I'd wait for the modding community. They will surely come up with something.

What I do is that I put my helmet in my favorites. Then, I can put it on or remove it quickly, whenever I want to see my character face. Otherwise, I don't think there is an automated way.

There is a mod for this now: No Helmet Mod. Make sure to read the description and contact the author if the helmet you want hasn't been changed by the mod.