If you've ever thought about screencasting , but the cost of the software was prohibitive, here's a thought: try Jing!
I was at MacWorld last week, channeling my inner Apple fan girl, and Tech Smith , the makers of SnagIt and Camtasia, were there talking about the coming-soon Mac version of Camtasia . As an aside they were also showing off Jing , a free, cross-platform screencasting tool. The only limit is length: each Jing screencast can be no longer than five minutes.
As an example of how easy it is to use, here's a little screencast  I made about Google Docs. It took me about (surprise!) five minutes to make, total.