Ewan McIntosh posted about sketchcasting today, and caught my interest. Basically, sketchcasting mashes blogging with podcasting, only instead of words, you draw out your concepts, as a teacher would on a whiteboard. The possibilities for online tutorials, visual learners, etc. seem really promising, especially in math/science, which (I assume!) rely heavily on diagrams, formula manipulation, etc. Here's the introductory video, but you can also view the "how to" on YouTube.