With Keoki we have to firmly say, "NO" and if he doesn't stop, we hold him under the neck – not tightly, just enough so he can't grab -- and make him sit. Then we look him in the eye and say, "NO! Enough!".
That usually does it for him, and he's getting better and better at either not biting and/or listening the first time.
He usually does stop the first time w/me, and in fact seldom does bite at me in play, but not as well with Dh and the kids . One of my dd's says it's because he's afraid of me, but that is not the case. He never cringes, he just listens to the Mama! I think he sees the other dogs and the kids listening to me, and the fact that I don't ask or beg him to stop doing things. I TELL him. I am working to get the family to see the difference, and to stop bouncing around while saying, NO. LOL