I recently relocated all of my AV stuff into a closet which includes my Slingbox. Everything is working great, but I miss having the ability to see if somebody is currently connected. It would be great if you added on-screen notifications to the Slingbox software so that a person watching the TV hooked up in-line to a Slingbox could tell if somebody is connected. A simple watermark in the corner would be perfect.
Expanding on this, you could even allow remote users to send pop-up messages to the TV which could be useful in situations where you would like somebody to change the channel on a non-IR device.
User connected notification
User connected watermark