I was at a company that hired a new IT director. He made it very clear at the beginning that he wanted to bring in his own people, so I had already been looking for a different position and had one drop in my lap but it was not yet finalized. We had an incident where there was a misunderstanding about doing some work on the weekend and he used it as an opportunity to "teach me a lesson" by chewing me out in front of my boss, telling me that "work came before even family". I politely told him I clearly understood where he was coming from. My new job came through a couple of days later and I turned in my notice. Little did he know that I can become great friends with his boss (COO) prior to his hiring, so when news came out that I was leaving, he personally called me into his office and asked me why I was leaving. I told him the truth. Although the IT director didn't get fired, he was definitely reprimanded for his actions.
But the best part was this. I served three roles when I was there: Oracle DBA, SQL server DBA, and an Unix administrator. After I left, he had to replace me with not one person, but three because he couldn't find anybody with my unique skills or even anyone with even two of the skills.
No words in an email could have provided an better parting gift than that.