Podguide.tv lists a few companies that are streaming nothing but ads to anyone willing to watch, AmEx and Nike Soccer among them. WebJungle and MicroPersuasion comment.
Also, check out this "vodcast" by BMW (is it me, or should be spelled "vodkast"?). The company also has a podcast and a series of audiobooks, as well as instructions on how to transfer content to iPod and PSP.
