He played Maynard G. Krebbs on Dobie Gillis and Gilligan (no official first name) on Gilligan's Island. He also did a few other shows no one but me seems to remember, The Good Guys and Dusty's Trail. But Bob Denver had another sideline - he not only owned his own radio station, but he and his wife did a syndicated chart-based countdown show for several years. 

It aired primarily in West Virginia and I'd loved to hear it if any airchecks still exist. Before Denver passed away in 2005, he used his money to start a radio station whose profits went to help special needs families. WGAG is a low powered FM (just 100 watts) in Princeton, West Virginia and is still on the air today. It calls itself "Little Buddy Radio." Unfortunately, it doesn't seem to be streaming any longer. 

But as the linked story notes, that wasn't Denver's only contribution to radio and TV. Casey Kasem apparently used his voice as an inspiration for Shaggy in Scooby Doo. 

Bob Denver and his wife had an oldies radio show