Idea about alarm and security
RobGR: I advise looking into setting up zoneminder.  You can get it from http://www.zoneminder.com/ .   It is a free linux program, it will integrate pictures from a variety of cameras and save them in a searchable way via a web interface.  You can make it trigger on motion, and only save those shots, and it will make little avi movies out of sequential stills from an ordinary still camera.In my experimentation, I found that ethernet based "web cams" worked best for my application.    I used the cheap Airlink brand sold at Fry's.  The quality is not good, but good enough to see who is in a room.  If you need to read license plates in a parking lot they will not be good enough.I believe a decent small business could be made simply building and installing zoneminder boxes.  I tried to get set up to do that but never really got that first customer.Another business opportunity is in higher quality cameras for zoneminder and similar applications.  Security cameras are really 15 years behind in picture quality, and to get decent quality you pay thousands of dollars.  I tried to use one of the common consumer cameras, via the control-by-USB mode, as a security camera, but the control by USB mode is buggy and unreliable on most of those cameras.If you made a simple ethernet camera like the Airlink 101 sold at Fry's, but had auto-focus, at least 3 megapixels, auto-correction for low light, I think they would sell well.