Didn't see another thread on this but I just discovered these things and they're cool if you travel a lot and use PowerPoint to present on the road. I don't know how long they've been around, but Targus and Kensington both make them - I found one for less than $20 and for the ease of use and functionality I wouldn't care if I lost one on every trip!!

Plugs into the USB adapter and it pages forward, back, opens the ppt file, etc from up to about 20-30 feet in range. When ever in a different country I never know what type of room set up to expect etc so this little thing is perfect for flexibility to walk around the room / engage the participants without being tied to the computer to hit 'page forward' etc.