In Mumbai, formerly Bombay, the tiffin, or lunch, is prepared by the wife, mother or servant of the intended. In the United States, because of little time (and a lack of a domestic staff), many of these lunches are prepared by outsiders, but the underlying principle is the same.
With the spread of these services, Punjabis can have their saag paneer and meat curries; Gujaratis can have their dal, bhat (rice), shak (vegetables) and rotis (flatbreads); and south Indians their rasam (tomato-based curry). And as demand for home-cooked food on the job has increased, so has the number of outlets providing tiffins.
I have not done it myself, but I can honestly say that this would be a pretty cool thing to have here in Atlanta. Alas, Atlanta's Indian population is probably a bit too thinly spread to make it worth somebody's while, except in a few areas. But I can dream, can't I?
Update: The fiance indicates that Bhojanic in Decatur does this.