When I use VNC or RDP to remotely control my office computer, as far as I'm aware, someone standing in front of my computer could be seeing everything I'm doing. Furthermore, if I lose my connection then the computer will still be logged in (i.e. not locked) so someone in my office could do whatever they wanted with my login credentials.
Is there a way to remotely access ones machine that doesn't compromise privacy from someone who may be physically in front of the machine?
EDIT: I'm using tightVNC or realVNC to access Ubuntu Linux. Sometimes I work with Windows machines too so the RDP answer is also valid/interesting.