Passing the CPA exam in one sitting. At the time I took the exam, there were four parts (given over three days): auditing, practice, theory and law. You needed to score at least a 75 on each exam to be given credit for that part. I studied hard, and it paid off.
At my former employer Blum Shapiro, to make partner one of the key factors is contributing to business development. Through past relationships, I was able to bring several significant clients to the firm. Not many CPAs focus on business development. To me, it is vital to the success of any business.