My youngest turns 3 this month. Her newest thing is throwing herself on the ground and screaming. I walk away as I'm saying, "Wow that's too bad." She's done it twice and received no other attention from it. One time was on the gym floor of the Y. The wokers thougth I was craxy, but it took about 30 seconds and she got up and came to where she was supposed to be.
I also totally agree with getting your husband on board. If my kids are stressing me out, disobeying or being mouthy, he'll say, "It is not OK to treat my wife that way." There's a lot of power in this statement for lots of reasons, but it works. Also, if I ask them, tell them, or eventually scream at them to do something, and he's downstairs (working) he'll come up and intervene on my behalf. If one of us feels the other didn't handle the situation right, we discuss it AWAY from the kids.
Finally, continue to be consistant. If you put her in time out, and she gets up, put her back. You're the mom.
Oh, another thing that works with mine - "Say, 'ok Mom'" Like, I'll say, "We don't smear peanutbutter on the chair." My child looks at me blankly with a hand full of peanutbutter. I say, "Say, 'OK Mom'." My child says, "OK, Mom, I need a napkin." I'm not sure why this works, but there's something in them saying it that they are commited to doing it. Now, sometimes mine won't say OK Mom, so I have to get a little louder and move a little closer and say, "SAY OK, MOM." Sometimes it requires a hands on approach, getting down on their level - eye to eye, gently taking their arms so they're facing me, and I say, "Say OK, Mom." And there it is, "OK, Mom." And at 2 they get it, they understand that they've just agreed.
I hope some of this helped. I think the key is to find what works for you and your daughter.