Bam! This place! You'll definitely have to check out Lupe's--great little taco shop that you (probably) didn't know existed.
Service is pretty much like chipotle (but the food is better)--walk up to the counter, pick a shell, meat, toppings and beans or rice. Two fantastic tacos for five bucks! I had the pork and steak both were spot on. Salsa selections were also very good.
This is my kind of place, simple menu, fun atmosphere, and great service. And hey, you can even grab a beer!