In Google Maps, the distance-measuring tool offers a choice of three unit systems: Metric, English or “I’m Feeling Geeky.” If you click the third one, you’re offered a long list of, ahem, somewhat uncommon measurement units, including parsecs, Persian cubits, and Olympic swimming pools.

Mac OS X’s text-to-speech feature, meanwhile, lets you endow your Mac with any of dozens of different human voices. Each speaks a funny sample sentence. The Fred voice says, “I sure like being inside this fancy computer.” The quaking, semihysterical Deranged voice says, “I need to go on a really long vacation.” The alien-sounding Trinoids voice says, “We cannot communicate with these carbon units.”

On YouTube, if you pause a video and hold down the up and left arrow keys, you trigger a secret game of Snake. Try to guide the increasingly long snake’s body around the screen with your arrow keys without tripping over yourself.

In each of these cases, some programmer deep inside these megalithic corporations exhibited a sense of humor—a display that somehow made it past committee, through the lawyers and out into the world.

In the olden days—10 or 20 years ago—this sort of playfulness in software was more common. Software engineers took pride in embedding into their code all manner of jokes, whimsy and Easter eggs (hidden surprises triggered by unlikely sequences of keystrokes).

Some of it was simple pride. Easter eggs often took the form of programming credits; after all, programmers usually don’t get any public recognition, not even in the user guide.

Often the buried humor in software consisted of elaborate inside jokes. In the original system software for the Palm Pilot, for example, programmer Ron Marianetti created an animated taxicab, resembling a fat Volkswagen Beetle, programmed to race across the screen at random times—a tribute to the Pilot’s original proposed name, the Taxi.

Across the hall, fellow engineer Chris Raff embedded an Easter egg of his own. If you held down your stylus in the lower right corner of the handwriting-practice game screen and then pressed a scroll button, a photo of himself with a buddy, tuxedoed at Palm’s annual Christmas party, would inexplicably appear.

In time, though, Silicon Valley’s corporate bosses began to frown on the practice of burying jokes in software. Part of the reason was quality control: by definition, an Easter egg is an untested feature. It’s a loose cannon that could, in theory, interfere with other, more important parts of the program. It made the overlords nervous.

Another problem was employee retention. When programmers buried their own names into their work, they were, in essence, advertising their own skills. Their names were clearly displayed for inspection by headhunters at rival software companies.

Finally, there’s the simple matter of corporate image. An Apple or a Microsoft or a Palm may spend millions to create a certain public image of professionalism. The last thing its image meisters want is some rogue animation of a taxi driving across the screen during an important public demo. (Which actually happened to Palm. The taxi Easter egg was removed shortly thereafter.)

These days, the spirit of in-jokes and whimsy lives on, but it has moved to new addresses: video games and movies—especially movies on DVD. Software jokes still live on in mainstream apps, but they’re less ambitious, and most of them seem to come from Apple and, especially, Google.

Inside jokes lurk on the icon for Apple’s TextEdit, for example (view the icon at the largest possible size). Or turn on the Mac’s Speech Recognition feature and say to your computer, “Tell me a joke.”

Or search Google for “recursion” and click the “Did you mean?” suggestion. Or call up the Sydney Opera House in Google Earth and then spin around to the waterfront side; a late, great TV celebrity waits for you there. Or ask Google Maps to give you the directions from Japan to China and marvel at Google’s suggestion for getting across the Pacific (step number 42).

Thank you, anonymous programmers; keep it up. You’ve made it clear that software can do more than make us productive—it can also make us happy.