Default [Q] Is there an App that just lets you see your phone display?

Is there (or technically, are there limitations that would prevent someone from creating), a Google Glass app that simply lets you view your phone display.

For example, maybe there's an app I use that's not a Google Glass app, for rxample - my app that lets me view my IP CAM live feed, or maybe a game that I want to keep an eye on passively so I can just pick up my phone when I'm ready to do my next move or whatever.

Does something like that exist, or can it? Or are there limitations in what developers can do that prevents this from ever working?