:bells and whistles: [by analogy with the toyboxes on theater
organs] n. Features added to a program or system to make it more
{flavorful} from a hacker's point of view, without necessarily
adding to its utility for its primary function. Distinguished from
{chrome}, which is intended to attract users. "Now that we've
got the basic program working, let's go back and add some bells and
whistles." No one seems to know what distinguishes a bell from a
whistle.
-- The AI Hackers Dictionary