I think it should be another MFD. If nothing was happening you might be able to link into your music files, and then it would be the screen for the MP3 player. If you were just hovering in space (such as a Nav Beacon) it might be used to look around without having to turn your ship (with a line on the sensor circle showing the cameras' line of sight). In combat, it could be used for different camera angles, with the default being that of a rear view mirror. Also in combat, maybe it could be used (from a safe distance so you are not currently being shot at) to lock onto a target, and then fire and guide a remotely controlled missile. When close in to a station it could help display docking information.