Wow, I wish I had some more constructive advice because we have the same problems with our 7yo. We've had them since she was about 2.

We have never come up with a good solution either. Punishments, rewards, positive reinforcement, timeouts, etc, and nothing works. The only thing we've ever had any success with is giving her time to calm down on her own. We put her in her room, and allow the attitude or tantrum to run its course. Sometimes she gets nothing she wants until she settles herself and does what's asked of her, but usually once this cycle begins, everything just makes her more angry. It's a vicious cycle.

What worries me is the anger. She gets so angry when things don't go her way, or when she's reprimanded, that I'm afraid this will turn into long-term anger issues.

I feel your pain, I really do. This situation has caused a ton of tension in our house, and it manifests itself in all kinds of unwanted ways. We're trying to understand that when she is fighting us, she's struggling with something, and we need to help her or give her time to figure it out.

I hope you can find some peace with it all. It is not easy.