Before you leave your summer job:
(1) Let people know you're leaving and set up lunches, coffees, etc.;
(2) Get together with fellow summer associates and buy thank you presents for the secretaries, word processors and others who made you look good this summer (and don't forget to write personal thank you notes);
(3) On your last day, drop in and say a personal goodbye to the people with whom you really connected this summer; and
(4) Feel free to send an email after you leave, asking if the deal you worked on actually happened, or the outcome of the lawsuit on which you assisted.