Williamsburg, Va.--B2B Works, an advertising network of business-to-business Web sites spanning 70 industries, launched this week. The new online network is intended to provide one-stop shopping for marketers looking to reach decisionmakers in an array of vertical markets. It includes more than 100 Web sites, including those of Architectural Record, Thomas Regional and Waste Age. B2B Works can measure ad performance within hours, allowing for on-the-fly customization and targeting of ad messages. Modeled after DoubleClick and Flycast Communications, which focus on consumer advertising, B2B Works is solely focused on business-to-business marketing. Online business-to-business ad spending is projected to reach $2.5 billion by 2002, according to Forrester Research.