The Legendary Shack Shakers mixes Appalachian folk with metal and punk. They are one of my fav bands. They have alot of influences so some you may not hear any folk in but the majority you do.

Golgol Bordello is gypsy/punk/metal they are really cool as well. Not as hard core metal as some of the bands mentioned. Balkan Beat Box is an offshoot band of Golgol Bordello and they are in the same vein. I dig both of them alot.

cya
JT