I have two free applications that make my life a lot easier.

The first one is Jing. Jing allows you to capture your screen quickly and share it with someone through a provided url. This is helpful when you are try to explain an error, usability, or quick tutorial.

The other application I just found today and it is called TeamViewer. TeamViewer is a remote desktop client that allows you to remotely control a computer. It is compatible on Mac and Windows and is very fast because of the scaled back graphics of the viewer. It was very easy to download and install. Not good for demos of software but great for troubleshooting computers/software.