Looking around the Podcast area of the new Zune Marketplace I stumbled into a vcast that should be a fun time-killer at work: Vintage ToonCast, Playing public domain vintage cartoons and high quality short films. Old Looney Tunes, Betty Boop, Superman, Popeye and others.
You can also add RSS feeds yourself, and suggest they get added to Zune's list. One I want to add when I get home is The IT Room. I've heard it's funny, I'd like to watch it some time and don't want to lose the link.
Especially handy for Zune 30 users: Zunerama's video tour of the new interface and features on the device and their software walkthrough for the PC end.