I've found LinkedIn to be very useful for keeping track of former teachers and managers. For example, a tutor who helped me a great deal in 1980 is now the hea

I've found LinkedIn to be very useful for keeping track of former teachers and managers. For example, a tutor who helped me a great deal in 1980 is now the head of his department and I have watched the slow but steady decline of a former manager who was a real challenge to work with. I also use it to keep track of former colleagues who were difficult to work with and avoid applying for jobs where they are working now. Even if I don't end up working with them again, it's an indication to me that those companies have a defective HR department so they've probably hired other difficult people too.