Is it possible to use my Macbook Pro's display to receive inputs from other sources?
Yes, but it's not worth it.
You would have to take the laptop apart, design and engineer a custom converter to drive the LCD interface (internally, it's going to use LVDS to handle the interface between the laptop's motherboard and the screen), and power it somehow. It also would probably render the macbook from which you removed the screen unusable as a laptop.
It would take a few hundred hours of engineering time, and cost a lot in prototypes.
You are better off just buying a separate LCD.
If your other input sources are networked computers that are on the same network as your MacBook? You could use a VNC like program such as ScreenRecycler to let other computers show their screen on your Macbook.
The Macbook itself will still need to work, but this would be one way of displaying video from other sources on your Macbook's display. You could probably even use the HDMI interface on BlackMagic's thunderbolt capture device to display the (DVI) video output from another computer. It'll be awkward and cumbersome, but should probably work.
Of course, the answer you're probably looking for is that you should just buy a traditional LCD monitor if you need a second display for your desktop. All of the solutions described above are considerably more awkward and expensive than doing that.
Well, not in the conventional sense. No you can't just plugin HDMI source and use the Pro as a monitor.
However, Napkin Studio is working to achieve AirPlay mirroring on the Mac. That is, you can mirror your entire iOS screening the Mac. Here: http://www.napkinstudio.com/
Also, there is conventional airplay, where you can just play the video that is on your iOS device on the Mac monitor. Again, this isn't from Apple(yet), rather from developers. Here: http://www.airserverapp.com/
So yeah, if you are in the Apple ecosystem, yes your Pro can receive input from other "sources". Venture outside the fruit world and.. NOP!