I have a "regular hatchet" (not a roofing tool, or shingling or drywall hatchet hammer, or carpenter's hatchet) that has a hammering nub sticking out the back of the head. I bought it at Wally World a couple years back and the brand name sticker has peeled off the wooden handle (shucks). I modified an army surplus axe head sheath for it to fit in.

By the way, here's what I've just heard called "roofing tools" being marketed as a survival tool or "hatchet hammer" it looks like for real cheap: I used to own one like it and got rid of it. I found it pretty useless as far as weight and balance are concerned and would rather have a prybar and hatchet separate.

http://survivalsolutions.com/store/product71.html