If you're feeling lucky and have the time, you can show up an hour or two at certain Broadway shows for a ticket lottery. The tickets aren't free, but are usually good seats for a very discounted price. You can put your name in for one or two tickets and every body in your party can put their name in, thus increasing your chances. All you need is cash and a photo I.D., and you must be present to win. I don't put my name in often, but I've been lucky enough to win for Dirty Rotten Scoundrels, Rent, and The Drowsy Chaperone.
Put your name in at these shows:
Avenue Q: This lottery is every day at the Golden Theatre on 45th Street, 2 to 2½ hours before curtain. The drawing is held 30 minutes later and if you win, you get to buy a ticket for $21.25 cash each.
Hairspray: Lottery sign up at the Neil Simon Theatre on 52nd Street begins 3 hours before curtain. If you win, you get to buy a front row orchestra ticket for $25.00 cash each.
In the Heights: The lottery is every day at the Richard Rodgers Theatre on 46th Street, 2 to 2½ hours before curtain. 30 minutes later, if you win, you'll have a front row seat for $26.50 cash each.
Rent: The lottery is every day at the The Nederlander Theatre on 41st Street, 2 hours before curtain. If you win, you'll have a seat in the first two rows of the orchestra for $20 cash each.
Wicked: The lottery is every day at the George Gershwin Theatre on 51st Street, 2½ hours prior to curtain. 30 minutes later, names will be drawn for 28 front row orchestra seats for $25 cash each.
a tosser friend has pointed out that [title of show] has a lottery too! It's the same as above - show up at the Lyceum Theatre on 45th Street with cash in hand and put your name in the hat. [Break a leg!]