I know of one good use for Bluetooth
I give a fair number of presentations and have found Bluetooth very helpful for that. I have a "presenter" (manufacturer's name for it) I hold onto which has a laser pointer and the slide advance/back/darken screen buttons on it. The computer side is a tiny Bluetooth dongle that plugs into a USB socket on my laptop. It works Impress a treat. The dongle even stores inside the presenter when not in use. Very handy little gadget.
Biting the hand that feeds IT
