City data catalogs are fast moving from the exception to the norm for large U.S. cities.
Washington, DC's Data Catalog, spearheaded by former CTO Vivek Kundra, was an early leader. The site combines hundreds of static government-created datasets from across DC government with administrative feeds like the city's 311 system. Their site emphasizes providing data in multiple formats, including where possible formats that don't require proprietary software. Kundra's selection as the nation's first Chief Information Officer, and launch of the federal government's Data.gov has elevated the principle among the federal government's vast datasets. DC's two "apps" contests sought to encourage creative uses of the data made available, and some of which are available at the DC App Store.
Beyond DC, many big cities have recently launched or are planning open data catalogs of their own.