I have a cut of meat labeled "chuck neck." It's boneless. What can I do with it?

I use beef neck in soup often (though with bones.) Very flavorful - like short ribs or shanks, but much less expensive. Depending on how much you have, use it in soup, stew and such.

You could cube it and make chili or stew.

So while I can't find anything labeled exactly anything "chuck neck" that is boneless. Chuck cuts in general have more tendons and connective tissue are are generally too tough to grill or broil. Longer cooking in a wet environment is what you want. So I would braise it for a few hours to make it nice and tender falling apart. Just choose your favorite spices and have at it. A pressure cooker would make quick work of it I bet if you have one.

Let us know how it turns out whatever you do with it.