Code V745 will get you 20% off Northeast Corridor unreserved trains. So far, so good, just like many other discount codes.
This one is also good on Acela Express and Metroliner trains all day Saturday and on Sunday except between 1pm and 6pm.
I’m told that this code also produces double Amtrak Guest Rewards points, but I see no mention of it on the terms and conditions. The offer is supposed to be good on Boston trips, but I’ve tested it on New York-Washington, DC and it works as well.
The code is good through June 22nd except for April 8th – 12th and May 28th – June 1st.