Resources
Here is a growing list of resources related to Mac screencating and presentations. It's by no means all inclusive. However, I hope to provide a resource for external tools, thoughts, and techniques related to screencasting.
Mac Screencasting Applications
ScreenFlow is the leading Mac screencasting tool by Telestream.
Camtasia for Mac is from TechSmith, makers of the leading PC applications SnagIt and Camtasia.
Microphones
Samson CO1U is a solid performer. I use the newer, CO3U model myself.
SnowBall is another popular microphone.
Discussions
Screencasting as Art by Brooks Andrus explores the cinematic elements of screencasting.
The Harsh Truth about Screencasts by Michelle Schoen proposes her AIDA model.