I suggest having a bell to ring for students who are waiting in line to use the computers to work and can blatantly see numerous people surfing on facebook (or the net, or watching sports videos). I don’t think facebook should be banned because checking out or communicating on facebook is fine. But it sucks to wait for a computers when you can see others checking out photos and status updates.
Because of the lack of social etiquette perhaps the library could post reminders on the computers that goes something like. “If you notice the computer lab is full or people are waiting in line respect your fellow students. Please refrain from surfing facebook if others are waiting.”
You are not alone in your frustration, as evidenced in the recent post Using Computers for Non-Academic Purposes, and the rest of the thread on computer workstations. Notices that computers are designated for academic purposes appear as a screensaver on almost all workstations and at the top of each login screen, but perhaps it is time to look at making more visible signs. Thanks for your comment.