Not sure how many of you maybe using this already (I have been for a little while now), but it is a great imaging tool for your PHD Guiding setup when things go wrong (i.e. when a cloud jumps in the way of your guide star etc).
With this program, when something does go wrong with your PHD Guiding, it will send you a little SMS text message advising that your guide star has been lost.
This is a free program and can be downloaded from http://www.mainsequencesoftware.com/PHDEmailer.html. Same creators as the WifiScope program that I also use with SkySafari (simply great). If you do decide to use the software please consider making a donation to these great developers!