You can join tdf.org for $36 a year and get discounts to some of the shows. Plays are $41 and musicals $47 plus fees. They use these to fill in empty seats and you can end up with a good seat for peanuts. It's a crapshoot though.
I know that this isn't exactly the topic but it is odd that Broadway is one of the only forms of entertainment that does not offer discounts related to out troops. Broadway perhaps is not seemingly the most related thing to military but I think it could atract audience members even if it was a minor discount. Even if it was only for a few shows related to the military (ex. On the Town, etc.) (I'm really blanking) I think that it would be apreciated. From the people who have served that I know they really apreciate the notice that they did that for our country. I definitely think that the addition would bolster rather than decelerate sales.
I appoligise for any spelling mistakes. I may be on my mobile. Clumsy fingers and small little touchscreen keys don't mixx. I try to spellcheck, but I may miss something.
I does look like you can call the NYC USO (212-695-6160) and see if there's any discounts, but I've never tried this. Are there any shows you are looking at in particular?
A little bit of military trivia. The original USO was next door to the Lyceum .During the run of Ben Hur, it was turned into the Ben Hur bar. No idea what happened after that.