In 2005, Greenstein wrote a book titled Ace on the River. Tuan Le, a WPT Season 3 champion, claims that book showed him how to succeed on the poker circuit. Greenstein is known for giving away a free copy of his book to the player who eliminates him in a tournament, including his autograph and details of the hand. Greenstein taught former girlfriend Mimi Tran how to play poker in exchange for her teaching him how to speak Vietnamese. He also plays online at PokerStars, under the alias "barryg1" and is a member of the cardroom's Team PokerStars.
He was also bet $10,000 by the 2+2 Poker Forums to say "lol donkaments" on an episode of High Stakes Poker, which he did after winning a hand against Erick Lindgren. After the initial $10,000, he also received a further $27,000 in donations from other charitable poker players who were amused by the bet.
Greenstein has three World Series of Poker bracelets.
He has also won two World Poker Tour (WPT) titles:
At one time, Greenstein donated all of his tournament winnings to charities, primarily Children, Incorporated, and he is sometimes called the Robin Hood of poker.
As of 2008, his total live tournament winnings exceed $6,400,000.
| Year | Tournament | Prize (US$) |
|---|---|---|
| 2004 | $5,000 No Limit Deuce to Seven Draw | $296,200 |
| 2005 | $1,500 Pot Limit Omaha | $128,505 |
| 2008 | $1,500 Razz | $157,619 |