For thousands of years, specialists ruled the business world. There was the blacksmith, the gun maker, the baker, the candle stick maker, the saloon keeper and the restaurateur, among others. Then came a period in the middle of the 19th century that ushered in the era of interconnected services and products under one roof. According to the Lower Manhattan Development Corp. , Irish-born entrepreneur Alexander Turney Stewart in 1846 launched AT Stewart, the country's first department store, on Broadway's east side between Chambers and Reade streets. The store offered European retail merchandise for low markups and set prices on a variety of dry goods, helping usher in an era of all-in-one shopping. Over the last quarter century, Wal-Mart ( WMT) gave new meaning to being all things to all people in the retail sector. In a sense, Wal-Mart became its own town everywhere it set up. Large advertising agencies that offered everything under one roof were a marketer's dream, because they could handle print, radio, television and Internet. Auto supply stores that also repaired vehicles and installed stereo systems were perfect for the hurried, non-discriminating consumer. Business has gone full circle and we are entering the age of the "specialist" or the "niche player." This isn't to say that this group didn't exist and has now reappeared. But I believe narrowly focused players again will become a bigger part of the business universe.