I've just treated myself to a slide changer for the computer. I think its one of those "why on earth didn't I get one earlier?" ideas.
(actually I think the reason I never got one before was I thought that they were really expensive, at least £50 or something).
My remote works with Mac and PC Powerpoint and Keynote (which is what I use) and means that I can sit myself on a beanbag anywhere i like and change the slides, or give a talk without having to worry about where my computer is sitting in relation to me. So simple, yet so efficient. It has two bits, the inner bit (which initially looks like a tongue sticking out)
pulls out and then looks like a USB pendrive. That goes into the USB slot. The other bit sits somewhere near you and you just click it and the slide changes. No wires, no mess, just nice slide changes whenever you like. Yay!
When I first bought it I had a brief "why isn't this working" moment, and then realised, I'd forgotten to put the battery in. It was hiding in another part of the packaging (oops).
Oh by the way, the one I got was called the Interlink Presentation Pilot Pro Remote and cost 23.49. Not too bad at all really!