RescueTime takes this idea, but also tracks the usage of desktop applications. "RescueTime is a web-based time management and analytics tool for information workers who want to be more productive. [It] doesn't record what apps or sites you have open, but rather what app or site you are paying attention to!"
RescueTime installs a desktop client (available for Windows and Mac) that monitors the web sites you visit and the software you use. The data is sent to a web application that processes it and displays statistics. For now, you can only see the domains, subdomains and apps sorted by the time spent and details for each item, but it would be interesting to see information about navigation paths and individual web pages.
If you don't like the application or you're concerned about your privacy, RescueTime lets you delete your data. It also makes it clear in the FAQ that the application only monitors "the names of the apps and sites you use and the times that you use them."
