Let's Make a Mathcast!
This is the title of a presentation Jim Dornberg (Monroe County ISD, Michigan) gave at the 2009 MACUL conference to a large and appreciative audience.
His presentation slides are extraordinary.
He shares many resources from his presentation.
He used a back channel powered by Today's Meet (by James Socol) for his presentation (kind of like Twitter but just for his presentation).
Jim has given quite a few presentations and has archived them along with many resources here: https://jdornberghandouts.wikispaces.com/