My dept. has a system of allocating each new PhD student to an existing one as a kind of buddy/mentor for the first few months, i.e. as a 'friendly face' to ask where things are, how to do things like setting up email/access cards etc...but in my experience it doesn't really work!
Personally, my 'buddy' was absent on the actual induction morning...and I have only seen her in the office once since then! This seems to be an odd theme in that those who volunteer to be buddies are those who are least often in the office...what's the point in that?
Luckily there are others who are in almost every day and most of the day who are willing to help out with printing instructions, directions to the kitchen, and how to swap TA timeslots...