This is basically the most amazing thing I've discovered in a long, long time. I'm going to be building a mount for my Wiimote so I can aim it at basically whatever screen I want and turn any computer into an IR whiteboard.
Also: To make it easier to tell where you're aiming your IR light pen, you can attach a red laser pen to your IR pen, then simply check that they're aimed at the same point at all times (having the two diodes as close to each other as possible will help). Keep the red laser running (so it's always pointing), and just press the button on the IR light pen when you need to use it. This way, you can point at whatever you need to on-screen, see that you're pointing at it and be certain of it, then interact with it. It'd be exactly like a mouse in every single way.
SW-5120-1900-6153
