It's often not easy to collaborate with someone while you are talking to them on your mobile phone the problem is that not all devices allow you to use the touchscreen while on a call. Even if you can use the touchscreen, it's usually too small to make for comfortable work. Researchers from the University of Duisburg-Essen have an interesting and bulky concept device that makes collaboration using your phone easy.
The phone has a pico projector integrated into it and the projector beams a screen that appears to be the same size as two tablet screens. One of the screens would be the user's smartphone and the other is the other persons screen. It seems you can drag things from one screen to the other for sharing or working.
The prototype is bulky and not something most folks would use in the real world. However, we have seen patent apps and pics of phones already that have tiny projectors inside. I can see this coming to market at some point and it would be cool. Apple is the company on one of the patent apps for projector phones. Check out the video below to see the prototype in action.