Looking for detailed digital media usage data? Think outside the Nieslsen box (that is usually closed and taped up at the seams, at least to academics). EMarketer is a great source that aggregates, filters, and organizes data on e-commerce, digital marketing and media from over 4,000 global sources. Its reports cover all aspects of the market with overviews, insights and analysis. Besides going to eMarketer for specific data or that perfect report on Social Media Measurement, you might want to beome a daily reader of The eMarketer Blog. If you think about it, no one is more interested in media usage trends than advertisers so even if the advertising angle is not what you're after, this is fertile ground for digital use data in the United States and around the world.