I sometimes will check to see the past cites visited too, But I have never signed in on someone else's aim or forum account. Then again I have only had the opportunity to do it a few times. I would say a bigger privacy infringement issue is the use of remote access programs like VNC Viewer from
http://www.realvnc.com. These allow you to access another computer through your own computer. You can watch what people are doing on the computers and in-fact control them. I saw that one of the public computers in a computer lab had the program on it (it shows a small vnc icon in the bottom right when active). That’s why I would never check my financial accounts or anything important to me on a public computer.