It's just cabbage, salt, and maybe a splash of water to make sure it's covered in liquid (if you can't get enough cabbage juice after pounding). I added caraway seeds, in german style. You leave about an inch of air in the jar and I just use the regular metal lids that come with the jars. I figure my food doesn't ever actually touch the lid, so it's not a big deal. That reminds me, I should go eat some.
A friend of mine made some raw sauerkraut and she added some raw miso. Couldn't really taste the miso but she was thinking maybe it adds to the fermentation.