When giving demos of ongoing projects to management or users, it would be nice to have a systematic way of directing their attention to a specific region of the UI. One thing I would really like is a tool that I can install in the background, activate with some customizable key sequence (ctl-meta-hyper whatever) and then draw regions of the screen which would then either highlight those regions or else dim the converse region. I've tried searching for such a tool, but only come up with screen-grab utilities which isn't quite what I want.
What do you use to manage viewer attention during demos (particularly in a teleconference where some of the audience may be remote)?