When everyone else is playing the drudge, it's nice to be able to play. For weekend workers, those weekdays off can be sweet revenge.

There are, in fact, any number of ways to a weekday diversion that's out of reach for the Sunday-fun majority. And a lot of them happen to be free.

Take bird-watching, the easy way, at the Audubon Naturalist Society, 8940 Jones Mill Road in Chevy Chase. You can spy ruffed grouse, snowy owls and common loons -- plus 181 other species of North American birds -- simply by strolling into the Wilbur Fisk Banks Memorial Collection, open Monday through Friday, 9 to 5, closed Saturday and Sunday.

The birds, of course, are stuffed.

But Charles Lawrence, curator of the Washington Navy Yard's Combat Art Gallery, is pretty lively. If you visit him (in Building 67, Monday through Friday, 8 to 4:30), he promises to do his level best to show you any painting, depicting scenes from World War II to the Apollo moonshots, you care to see.

"The other day, there was an old man who came in all bent over, and said, 'Bet you don't have a painting of the paratroop jump at Corregidor," Lawrence says. "I told him, 'Betcha I do,' and when I found it, he pointed and said, 'i'm one of those paratroopers.' When the old fella left, he was standing tall,"

If Greenwich Mean's your thing, you can tour the Naval Observatory, Monday through Friday, 12:30 and 2 p.m. (that's Eastern Daylight Time). The guided excursion, which begins at the front gate at 34th and Massachusetts NW, includes a short flick on how times are determined through the positions of stars, a discussion of electronic clocks and a visit to the observastory's 26-inch telescope. If you arrange a nighttime tour and the sky is clear (call 254-4569 for partculars), stargazing may be thrown in for good measure.

Want provocative conversation? Try the Kennedy Center's National Town Meeting at 10:30 Thursday morinings, when the likes of seaman Jacques Cousteau, pundit George Will and critic John Simon show they can talk a good game (call 223-0283 for program information). These panel discussions, sponsored by Mobile Oil, usually end soon enough for you to catch the noon Performing Arts Symposium, a behind-the-scenes look at the Kennedy Center's shows.Performers from productions of the Peking Opera, "Richard III" and "Sweeney Todd" are scheduled to talk in coming weeks (call 254-3718).

Speaking of speaking, there's oratory galore at the House and Senate, plus the occasional scandal-filled hearing (check your newspaper for showtimes). And the District of Columbia City Council meetings, every other Tuesday on the fifth floor of the District Building, sometimes are good for a chuckle.

But maybe the saga of drinking water is more your cur of tea. The Washington Aqueduct's Dalecarlia Filter Plant, which makes the Potomac potable for the District and Northern Virginia, usually can be toured by appointment. "We go through the whole water-treatment process," says Harry Ways, manager of the plant at 5900 MacArthur Boulevard NW, "There's a smell to it, but not a disagreeable ordor, if that's what you mean. The Potomac River is a perfectly fine river with perfectly good water." Try 282-2701.

Dulles Airport also is available for a look-see, weekdays 8 to 4. The self-guided tour starts at the airport poerations center in the main terminal and includes the John Foster Dulles reflecting pool in the south wing, the west terminal firehouse and the observation deck. For $52.07, the same price the airlines pay, you can ride one of those mobile lounges out to where the planes park. If this sounds intriguing, call 471-7838.

For an insight into the real world, you can visit the Safeway warehouse in Landover (341-6571), the Coca-cola Bottling Co. in Alexandria (820-2323), the General Motors factory in Baltimore (starting October 20, call 301/955-9508 and ask for Irv Galliher), Washington's main post office (523-2001) and , of course, D.C. Metropolitan Police headquarters (334-7973).

For an insight into how the real wolrd is portrayed, The Washington Post gives tours Monday, Wednesday and Friday (by appointment, call 334-7973), and WDCA-TV Channel 20 in Bethesda will let you see the inner workings of television. Contact Stephanie Campbell at 654-2600.

If you want further weekday amusement, you can always haggle with the phone company, have your car inspected or get a marriage license.