On a whim, I bought a KBGear "JamCam" from a local store. This is a very inexpensive digital camera, able to save images at 640*480 resolution. It has almost no features, and can hold 8 pictures at a time, unless you buy additional memory.
An example of the results that can be obtained are these pictures of my part of my study. Notice how the dog has snuck her way in to the second picture at the crucial moment. There is also a better picture of the study, taken with a Kodak DC280 camera. Susie has made her way into this one too. My wife would say the study needs tidying (and she would be right).
On the positive side, the JamCam was only $50 Canadian - say about $35 US.
I had some trouble getting it to work, using the serial port connection. I could not get it to work at all with a Pentium 120, but was successful with a Pentium 933 Mhz, and later with a Pentium 4 1.8 MHz. Nor was I successful with a Pentium 2 200 Mhz NEC laptop. All of these machines were running Windows 2000 at the time. Downloading pictures is quite slow, and the camera is very heavy on its 9 volt battery - I could take and download about 24 to 36 pictures with one battery, costing about $5. So it is not much cheaper than film to operate!
The JamCam also has a USB connection, but I was not able to get this to work on any machine I tried.
The results are of modest quality. It works best in bright light outside, and gloomy days give less satisfactory results. Flash pictures indoors are quite good, provided the subject is not too close, in which case they get over-exposed. (They are also out of focus, as there is no focusing method on the camera, so it is best to keep your distance.)
I was surprised to see that the USB connection is supported on a Linux system running gphoto2. (Gphoto2 is the open-source product for working with digital cameras, and is capable of working with an ever-growing variety.) I downloaded a copy to my FreeBSD machine, and attempted to compile it, but was not fully successful, as there were some missing libraries. I will follow this up "when time permits".
All in all, it has made an interesting introduction to digital photography, but the main result has been to make me covet a better-quality camera. I was able to borrow a Kodak DC280 from work, and the results were far, far better.