Sketchcast - from the site itself: 

Sketchcasting is a new way to communicate something online by recording a sketch, optionally with your voice speaking. Any sketch can then be embedded on your blog/ homepage for people to play-back, and you can also point people to your sketchcast channel here (or let them subscribe to your sketchcast RSS feed).

Sketchcasting is new but it's based on an old principle: the whiteboard (or the napkin in a bar) on which you sketch something to get a concept across... or to just have some fun.

Adding narration makes it infinitely more interesting, at least to me.  Take a look at my poor drawing below as I "walk you through it" vs the second one by someone who is obviously more talented than me artistically (not too hard to do, by the way) and is not narrated.  We love to hear the voice!!!

Obviously a talented artist. But I would like to have heard as they drew.  Maybe it's just me, though.