I won’t lie to you, I found out about this great free application from Lifehacker one of my all time favorite blogs. I’ve posted before about using QuickTime on your Mac to record your desktop and GoToMeeting sessions, it works but you’re forced to capture your entire desktop.
The release of a free new Mac App called Screeny now makes it even easier to record on you Mac. Screeny gives you the ability to record part or all of your screen, plus automatic uploading of the QuickTime file when you finish. It will record the audio from your Mic but depending on your Mac hardware you may still need to use a loop back cable to route the speaker audio to your Mic input, as detailed here in my original post.
Update 10/4/2011: It appears Screeny was only free for a day. An alternative is Jing which has a free version or you can follow my original guide and use the built in feature of QuickTime.