Here's some software I just discovered: Jing.
Jing is quick and easy screen capture software, created by Techsmith. Their giving it away right now as sort of an open beta in order to get feedback and work on features.
Jing is fun to use; it resides in memory, but once you want to capture your screen, you click to activate it. It captures both images and video and lets you share it online by creating account on Techsmith's Screencast site. Once uploaded, you can send a link to see the video or image.
It's especially handy for giving instructions. Instead of having to describe everything over the phone, you can screen capture what people need to do and send them a link. There's even annotation and audio.
I don't know how long this will be free, but you might want to check it out.