As I mentioned early this morning, the DVD set of the 1967 Spider-Man cartoons came out without the special features. However, there's an interesting special feature that was separately prepared for the Internet by some of the voice actors who worked on that series. It tells you who they were, how they were cast, what they're up to now, etc. The site is also a pretty amazing example of what one can do with Shockwave animation if one is clever. (But it's pretty elaborate. If you have a dial-up connection, you could be there a long time.)
Buried within the presentation is some info on the voice cast of the 1964 Rudolph the Red-Nosed Reindeer special, which included a number of the same actors. I can think of at least three people who regularly read this site who will consider that the most important piece of info I've ever dispensed here.