Zooming tools are very useful whenever doing a presentation or training. It helps both the people at the back of the room, as well as drawing people’s attention to the area of the screen you need them to be looking at.
On the PC I’ve used ZoomIt, which is part of Microsoft’s SysInternals tools.
Recently I’ve found Zoom It for the Mac, which is cheap, and works like a charm.
Claudio Lassala's Blog 