AKA: sub, grinder, hero, hoagie, wedge, zep, or torped
I grew up in upstate NY where Sub's were a staple take-out food - and I'm shocked that I can't find the equivelent in NYC. The traditional sub shop has the perfect mix of great bread, quality meats and fresh toppings.
Take the subway over to Astoria Queens to Sal, Chris and Charlie. They are well known.
Sal, Chris and Charlie Deli
3312 23rd Ave
Astoria, NY 11105-2203
City Subs (http://www.chow.com/places/22411) in Park Slope, Brooklyn. This shop is apparently owned by a former sushi chef who makes his subs with the same care as one would use for sushi. He uses the freshest, most flavorful ingredients and is very thoughtful about keeping things that should remain cold (lettuce, tomatoes, etc.) away from things that should remain warm and toasty (bread, cheese, pastrami, etc.) until the last minute. Everything is remarkably clean, too. Best subs ever!