Stand-up comedian Steve Mazan has made it his life mission to perform on Late Show with David Letterman, which is a mission many stand-ups in this generation share, but Mazan's mission really has been about life or death since he was diagnosed with cancer. So he launched his "Dying To Do Letterman" project, and filmed it as a documentary. He talked to Letterman vets such as Brian Regan, Ray Romano and Arj Barker. He went overseas to perform for the troops. He got two sets on Late Late Show with Craig Ferguson. Friends of his recommended him regularly to Letterman's booker, Eddie Brill, but it would take years of working with Brill to get his set from OK to Letterman-worthy. He would not get to win his appearance or have it granted a la Make-A-Wish.
Here's a clip that Mazan uploaded to YouTube on Oct. 1, 2008: