And what heavy stuff it is. You get both real-time and historical data about your visitors. Woopra tells you where they are, what browser and OS they're using, their screen resolution, the referring pages, and more. Needless to say, these are all hugely useful for designing a site your readers can understand and enjoy. You can even look at the data of individuals as they visit your site. (Although you see individual IP addresses, the visitors are personally identifiable only if they opt to be).