Fun: receiving packages.
More so: gleefully mailing packages to other people.
Best yet: sending messages via unusual means with the goal of surprising someone - and succeeding. I love surprises.
"Federalist blogwench" -- Fenno
"[A] caricature of Goffmanian anxiety." -- M. Vanderwheel
"[R]ude, cruel, and shows a blatant lack of open-minded understanding." -- Twilighters Anonymous