I recognize the name Pete Barbutti, but I'm afraid that's as far as it goes. And of course (being neither Canadian nor--horrors--a hockey fan, Howie Meeker means nothing at all to me. But Mel Blanc, now....Thanks for the tip on that David Letterman interview, I went directly over and watched it!
Speaking of voice actors--Mel Blanc was without doubt the first and best, but there are a bunch of British actors that do quite a lot of radio, even after they are successful in theater, film, or television. Did you happen to catch the BBC Radio 4 production of Neverwhere? (I believe it's available as an audiobook now.) Wonderful stuff!