Interesting. Here’s a small-footprint keyboard and trackpad combo with the obvious oddity being that the keys are on one side while the trackpad is on the other. The Econo-Keys EK-76-TP is designed “for medical and industrial environments” by being easy to clean and resistant to dust and dirt. Oh, and it costs $131, so it’s not exactly consumer-friendly. But the idea’s there.
If you had a netbook and, for instance, you hated either the machine’s trackpad or keyboard (but not both), something like this might work — provided, again, it didn’t cost almost half what you paid for your netbook. The keyboard measures 8.91” x 3.54” x 0.38”, so it’d likely fit inside your laptop bag.
Maybe use the trackpad for surfing and then flip the thing over once it’s time to really hunker down and type up some sweet tech news. Or maybe it’s just a dumb idea altogether. Whatever the case, it’s clearly got some sort of use to someone, somewhere.