I confess I'm addicted to listening to podcasts. In particular, I like listening to them on the bus on my way home after work when I'm kind of brain-dead, but still need to do some work. I also like accessing information on my own terms and podcasts allow me to listen anywhere – even in the bathroom!
It's easy to find great radio-based podcasts (I love CBC Radio 3 & NPR's All Songs Considered for example) but informational podcasts on something other then technology (and the wonderful grammar girl mentioned in the previous post) are more difficult to track down. However, McMaster's Centre for Student Development has developed a useful series of video podcasts that are short (usually under 4 minutes) and to-the-point. These podcasts present time management, writing, math, and learning tips. I really like the one podcast called "winning through wedging" (as opposed to "winning through wedgies"). They also come in a variety of video formats: video iPod, mp3, Flash, Quicktime and Window's media.