Keep the lines of communication open to people who can help you in the future. Don't act too elated about your new position or too angry about the job you are leaving. Nothing makes enemies more quickly than jealousy over your new job or resentment over how you have treated those around you. While most businesses have become more enlightened over the last decade, there are still those that engage in both subtle and overt abuse of their employees. Whether this involves financial exploitation, psychological or physical abuse, no employee should have to face it at all.
Abuse needs to be addressed at the first instant it is experienced.
If you find that your manager berates employees in front of your peers, has shouting matches with his partners or tries to intimidate employees physically you must call him or her on this behavior. Sometimes this can lead to your dismissal, but in most cases you would probably leave of your own accord if this behavior was your manager's standard way of operating. Don't let a bad situation spiral out of control. Abuse, in any form, has no place in the office. While it doesn't happen that frequently, getting involved in business situations that are on the fringes of the law can destroy not only your career, but your entire life.