I know this is an old thread, but the Marantz SR9600 uses IR to send feedback to a customized RC3200 remote control. On-screen you can see details such as current input, volume level, sound processing mode, active channels, sleep timer etc. It even knows when the unit is in standby (versus covering the remotes IR receiver where all status indicators go blank).

And you know the original Pronto? How IR codes are learned from the IR eye on the bottom? Not many people know that there's a second IR receiver on the FRONT of the unit, originally intended to be used for IR feedback just like this.