IR extenders have been around for a while now but they generally require you to run more cable through your house and stereo cabinet. The InjectIR from Sewell doesn't—it borrows a cable that's already there.
Instead of using a single, continuous cable to transmit the IR input from the remote to your hidden devices, the InjectIR uses dual adapters that fit on either end of an existing HDMI cable to send and receive signal. The visible receiver fits between the TV and cable, using the not-often employed CEC channel to send commands. The hidden receiver needs to be plugged into only one of the video devices in order to control them all with their individual remotes. It's available from the Sewell site for $45. [Sewell via Ubergizmo]