The world's largest retailer is preparing to open a smaller box in a densely packed neighborhood in Los Angeles. Under the name Neighborhood Market -- essentially a small supermarket -- Wal-Mart Stores (WMT) will offer the only traditional-style grocery store in the city's Chinatown neighborhood. Wal-Mart isn't alone in following consumers back into urban cores. Target (TGT) is rolling out several CityTarget small, urban-format stores in Los