-How about going to see a taping of a show? The Daily Show, The Late Show with David Letterman, The Tyra Banks Show, The View, Saturday Night Live--all of them film here and the tickets are free. You may have to get on a waiting list, but once you get in, it's a good time.
-The Nuyorican Poets Cafe: This is a cool little cafe in the village that features some of NY's best up-and-coming poets, playwrights, and musicians. Every Friday night they have a poetry slam. They also serve drinks. And I believe admission is only $11.
-Check out a comedy club. Gotham Comedy Club has been completely renovated and looks great now. Admission I think is $12 and there's a two-drink minimum, but once you fill out one of those comment cards, you're pretty much guaranteed to "win" free tickets--which is really just their way of getting you to come back. So with drinks you'll probably end up spending $20 for a couple hours' worth of entertainment. Also try The Upright Citizens Brigade. They do a lot of improv shows and tickets are between $5 to $11.
-Chelsea Cinema's Classic Movie Night: If you must settle for dinner and a movie, why not go see a classic movie for only about $7.50? Not only are the tickets cheap, but they also give you a raffle ticket which can win you a free dinner for two, or off-Broadway show tickets, or movie tickets. It's pretty fun. I saw Niagra Falls and The Best of Everything there. Hysterical. Check it out online for a schedule. They show a different movie every Thursday night.
-This Saturday is Hip Hop Karaoke night at The Knitting Factory at 11 PM. Admission is free. And this is beyond the usual cheesy karaoke spots. They provide a stage, a hype man, music...it's like you're putting on a real show, but you're rapping to classic hip hop songs. Even if you don't perform, it's cool to be in the audience and just enjoy. I'm actually going to this.
-For more traditional karaoke, try Japas on 55th Street. Instead of having to rent a private room, which can be pricey, you just sing right at the bar and pay about $1.25 per song. Plus they offer a pretty extensive sushi menu and everything is half off. (I usually get the California roll for $2.50.) And they have happy hours too, so drinks are also cheap. You'll probably end up spending less than $20 to eat, drink, and sing.
-Dave & Buster's: This one is not exactly a hidden treasure, but dinner there is pretty affordable, and with some entrees you get a $15 playing card to play all the games there. (Skee ball, basketball, the trivia game...)
--Willing to venture outside of Manhattan? Then come to Queens! I just went for the first time to the Queens Farm in Floral Park. Admission and parking is free. Then if you want to do the pumpkin picking, hay ride, and go through the giant maze made out of maize, it's only $10 for a combo pass. And while you're there, you can feed the cows and goats and sheep. (A bag of feed is $3.00) And you can buy some delicious hot apple cider, fresh popcorn, and pumpkin muffins.
-Also in Queens, come to Flushing and have some dim sum. Sure, you could go to Chinatown in Manhattan, but why not change up the scenery a little? You can go have some dim sum (which will only run you maybe $10-$14 depending on how much food you get, since you pay per item that you choose), then head over to Flushing Meadows Park and see the giant NYC replica at the Queens Museum. (Admission is free, but they suggest a $1 donation.) You can also go to the Flushing Town Hall. They have all kinds of shows there--jazz ensembles, choirs, dance troupes, etc.--and admission is usually free or cheap.
--If you want to see a Broadway show but can't afford full price or even TKTS prices, why not try for lottery tickets or rush tickets? Not all shows offer them, but plenty do. I know for a fact that Avenue Q and Spamalot offer lottery tickets. So basically you show up at the box office before noon and put your name into a bin. If your name gets picked, you get up to 2 tickets for dirt cheap. I saw Rent this way for $25. And some offer plain old rush seats, where you show up early in the morning, before 9 AM, and depending on how many seats they have available, you can get cheap, cheap tickets. I saw Freak like this and paid $17 and sat in the first row.
--Spend a day at the zoo. The Bronx Zoo is free on Wednesdays. And the zoo in Central Park is pretty cheap from what I remember.
--Take advantage of Restaurant Week when it rolls around. You can have a 3-course meal at a 4 or 5-star restaurant for $20-$30.
--Go dancing. On Friday nights at LQ, they usually have a free all-you-can-eat buffet I believe at 7 PM and drink specials. Ladies are usually free until midnight and men get reduced admission if you sign up for the guestlist. Even if clubs aren't your thing, it would be something different to do on a Friday night. Plus free dinner! At the Copacabana they even offer salsa lessons before the live music gets started.
--Volunteer! Volunteering is a free way to spend a day, and you help someone while you're at it. Take a look at the New York Cares web site. They have volunteer projects all year long that you can take part in, and it can be fun. I've participated in the school and park clean up days, where we do everything from paint murals and benches, to help organize libraries. And as an added bonus, they usually provided free lunch and dinner. And especially going into the holiday season, they'll need volunteers to help with soup kitchens and toy drives and the like.
--Check out this web site: twi-ny.com It lists all kinds of stuff to do in NY: gallery openings, film festivals, book signings, etc. Most of the stuff is free or pretty cheap.
There is a lot to do in this city that won't break the bank. (Trust me, I don't make a lot, and yet I always have a good time.)