I was in college when Letterman started. He was funny. He wasn't a big part of my life at the time, but he was funny.
But stupid pet tricks and the like aren't what I remember most about Letterman. What I remember most is how he embraced amazing people and gave them a chance to strut their stuff.
Letterman recognized the dying talent of Warren Zevon, and he gave Warren the chance to end his talented life in the spotlight. To me this is one of the most amazing things David Letterman did...he gave Warren Zevon his chance to shine, even as he was dying.
And when Zevon did die, it was Letterman who announced his death and did fair tribute.
