Advisor's wife is having a baby, should we be getting him something? My advisor's wife is having her first baby and he told us about it at our last lab meeting.  We understand that this will mean he might need extra time/patience as the big day approaches, but are we supposed to be doing anything else?  What is the etiquette for this as one of his students?  Should we be buying him some kind of baby gift?
A personal gift from you, as an individual student, is not expected, at least by European or North-American etiquette. It may be nice to pool with other students and group members to offer a small gift (either something for the baby, or something for the father). It'd be more customary to offer it after the baby is born, rather than now.

On the other hand, there is no strong expectation that you offer a gift. I.e., if you decide not to for any reason, he won't think it weird.