Over at Bladeforums the general consensus is that Cold Steel Tommys are not the greatest.  
Ragnar's has a fairly good rep.
American Tomahawk makes some great tactical stuff.  Here's there link:
http://www.americantomahawk.com/index.htmH and B have a great rep for conventional tommys and pipe axes.  Here's there link:
http://www.hbforge.com/products/tomahawks.phpAs far as a digger/axe head, I haven't ever seen a hatchet or tomahawk so configured.  I've seen some axe/mattock heads at Home Depot, something akin to a firefighter's pulaski, but they look a little big for personal carry.
This is a pulaski:  http://en.wikipedia.org/wiki/Pulaski_(tool)