Screen+Casting+(make+video+demos)

ScreenR -- very simple web-based program to create screen casts.

ScreenCast-omatic --just click and go

Screencast -- a bit more professional looking, but still easy to use.

Jing -- I use this one a lot. It requires that you download software to your desktop, but it's very easy to use

Here's a list of some other tools you might consider (with brief explanations and links to each one)