Hey. I'm kinda had a thought and no idea where I might be able to find this but is there some sort of wireless button/light device out there? Like, the button can be placed upstairs and light downstairs, then someone could hit the button/switch upstairs to turn on the lite downstairs so that the person downstairs know that they are needed upstairs?

Kinda want to get something like this to help out my current situation.

I don't know if that's your case here: http://www.homecontrols.com/Categories/X10-Home-Automation

Does it have to be a light? What about a remote doorbell, you can pick them up quite cheaply from any hardware/electrical store.