As you probably have heard, David Letterman's final "Late Show" will be on tonight. Even though I hadn't watched Dave as much the last 10 years as I did in high school, I will miss him greatly.
There have been and are going to be a lot of pieces that will explain in much greater detail and with much more authority what an influence Letterman was on late night TV and on comedy in general. While his detractors might want to point out that he rarely won in the ratings war, comedy is hard to measure by ratings. Being funny and having broad appeal don't always overlap - in a lot of cases, they are directly at odds with each other. Particularly in his early years, Letterman was never one to sacrifice being funny for being appealing. He was unimpressed with the cult of celebrity. As Julia Roberts said to him last week, "stupid people annoy you."
Enjoy retirement, Dave.