Zaragoza
NYC's full of Mexican spots so high-end, you'd think Mexico itself was the land of milk, honey, and $23 seared turbot enchiladas. To get authentic food and atmosphere without incurring travel costs/kidnapping risk, hit Zaragoza Mexican Deli. 
At first glance, ZMD's nothing more than a tiny checkout counter and some shelves stocked with canned goods and cassettes of bands you might've once heard in, say, a Mexican deli. But behind the register, its ridiculously friendly employees have spent all day stewing up beef/chicken/lamb/pork to stuff into tamales, tortas, and $2 tacos so tasty you'd willingly spend $2.75 on them. There're also 11 seats in back, where you can leisurely watch televised soccer and drink 32oz Coronas you've pulled straight out of the beer cooler -- so casual it feels like it should be illegal, and will be if you execute your plan of pretending you didn't take any.
As you'd expect, Zaragoza offers takeout, but they also deliver -- because no matter what ethnic food you're devouring, nothing can beat your own apartment when it comes to sloppy authenticity.
