I am going to be adding my latop into my stereo setup a bit more by outputting its video to the TV and adding a Keyspan IR remote so I can control it with my Harmony remote, and see/navigate/control iTunes without having to get off my butt.
I needed an additional IR emitter for my Xantech IR setup. I bought 4 dual emitters, giving me 8 total, but I had only 3 of them in use and couldn't find the fourth. I did find an emitter from my old Hitachi DirecTV receiver, that was used for a TiVo-like function (before there was TiVo): you would tell the receiver to record something, and it would send an IR signal to your VCR to tell it to start recording.
So, I grabbed this IR emitter and tried to see if it could work with my Xantech stuff. But it didn't emit a red LED light like my other emitters, so I couldn't tell. Aha, but, I remembered, my DV camera has an IR mode. So I hook up the emitter, turn on the camera, light up the system, and sure enough, I see light coming out of the emitter, so I know it works. Very cool.