A button you can attach to your belt, cellphone or key chain which if you push will go to a selected person - parent, husband, best friend that will send an urgent alert with your GPS location so the recipient can come rescue the holder. While some phones may carry this type of one touch call/GPS technology, the beauty of the panic button is that it is less obvious to activate, smaller and less cumbersome than a cell phone, and potentially more reliable depending on the network and means of transmittal. I can see this marketted particularly for teenage/young girls going on dates or to parties - it could even get you out of a blind date that's going bad. It could be appealing for people with high-risk jobs, as well as people for people who've watched too many horror movies. Ideally it would be inexpensive, and the simplicity and discreetness is what would be the selling point.