In response to the request on the Europe forum - here goes:

1. See a Broadway play.
2. Visit Ellis Island/Statue of Liberty
3. Eat a hot pretzel from a vendor.
4. Window shop.
5. Meet someone under the clock at the Roosevelt Hotel.

Who has #6?

6. Stroll through Central Park.
7. View great art at the Metropolitan Museum.
8. Walk (run or bike) the Battery Park promenade.
9. Eat at an ethnic restaurant.
10. Have a beer on the 107th floor of the World Trade Center and look out at the lights over the Brooklyn Bridge and beyond.

Hasn't this thread been done before?

7. Take the Staten Island Ferry.
8. Go see a Yankee game.
9. If you "got game," go to a playground in Brooklyn or Harlem and take in a pickup basketball game. Better yet, see if you can get picked.

Visit the Empire State Building or World Trade Center Observation Deck at dusk.

Sit by the Bethesda Fountain in Central Park.

Stop by Rockefeller Center and St. Patrick's Cathedral.

Eat a bagel at H&H Bagel (Broadway & West 80th Street).

Take a tour of the New York Stock Exchange and see America in action.

I also have to second the idea of riding on the Staten Island Ferry. It's free and the view is wonderful.

Watch, or join, the disco skaters in Central Park on Saturday.

Take in the street performances in Washington Sqare.

Visit the Cloisters in Upper Manhattan for a fantastic view of the Hudson.

walk through the village
visit the 42nd st. public library
eat a corned beef sandwich at the second avenue deli
get a slice of pizza from your favorite pizza place
check out the architecture in soho

See Black 47 live at Connolly's pub. Only wear clothes you can spill beer on.

See the Blue Men perform.

See the toy soldiers and Fabrege eggs at the Forbes Museum.

Sunday brunch at The River Cafe.

Hear a dusk chamber music concert at BargeMusic while watching the lights of Manhattan come on.

Go to the Bronx zoo.

Take the Roosevelt Island Tram ( Cable Car actually ) over the East River alongside the 59th street ( 'Feelin' Groovy' ) bridge.

Buy a Knish or Hot Dog from a street vendor.

Hail a yellow cab from the street & go anywhere ( Safe ! ).

Ride the subway EVERYWHERE!
(forget cabs)
Enjoy a Hot Dog from a street vendor
Ditto Hot pretzels
Visit St Patrick's Cathedral
Visit the Vietnam Vets Memorial in lower Manhattan
Visit the Wall of Honor in Battery Park
Have a great time!
Welcome to NY

Take a walk over the GW Bridge or Brooklyn Bridge.
Have brunch outside at Bubby's
See a great foreign film at the Angelika
Have a Peach Dream w/soy milk (not apple juice) at Lucky's Juice Joint
Try on anything over $100,000 in Tiffany's
Gaze with admiration at the Dakota
Catch a free concert by the philharmonic in Central Park
Serendipity for dessert!

I agree with Ellen. . .Serendipity is the best place for desert.

MoMA for Van Gogh's Starry Night

Strolling through College Walk at Columbia University

Seeing "Rent"

Staten Island Ferry!

Take the Lincoln Center tour!

Oh, I almost forgot...
Take a tour of the New Amsterdam theater. The tour is free, takes about 1 hour, every weekday at 12:00 and 1:00 pm.

So many great suggestions, many of my faves already listed. Here are a few more.

Go to Katz's deli for any artery clogging, yet scrumptious sandwich

Stroll through Shakespeare Gardens In Central Park

Sit an outdoor cafe/restaurant and people watch

Eat a really good meal at Gramercy Tavern or Babbo (THE BEST!)

Run, walk, bike or blade on the West Side down through Hudson River Park to Battery Park and have an icecream cone at Custard Beach

1. Eat at Il Mulino (maybe not number one but certainly a good choice)

Don't forget to eat cheesecake at Junior's in Brooklyn.

Visit the Guggenheim.

Walk through the lobby of the Waldorf Astoria.

Do the walking tour of Grand Central Station.

Anne in Australia

go to the Frick Museum
check out the ceiling in the lobby of the Woolworth Building
Look for free walking tour of Grand Central - usually friday at noon
Free walking tour of Lower East Side - Sunday at 11
go to the Boat Basin at 79th & Riverside Dr.
take the #5 bus all the way up. Best sightseeing for $1.50.