A common technique is to run a VNC server within your deployed image. VNC (Virtual Network Computing) is a graphical desktop sharing system, which allows one to visually control another computer. The server constantly sends graphical screen updates through the network using a remote frame buffer (RFB) protocol, and the client sends back keyboard and mouse events. VNC is platform independent and there are several open-source server and client implementations available.
Pharo comes with a VNC client and server implementation, which can optionally be loaded. It is called Remote Frame Buffer (RFB). Unfortunately the project is not officially maintained anymore and the latest code is broken in Pharo, however you can get a working version from http://source.lukas-renggli.ch/unsorted/.
Install the RFB package, define a password and start the server. Now you are able to connect to the Pharo screen using any VNC client. Either using the built-in client from a different Pharo image, or more likely using any other native client. Now you are able to connect to the server image from anywhere in the world, and this even works if the image is started headless. This is very useful to be able to directly interact with server images, for example to update code or investigate and fix a problem in the running image.