Track Time Spent in Applications and Productivity in OS X, Windows, and Linux
Two apps that can help you track the time you spend in various applications like your IDE, web browser (firefox, IE, Safari, etc.), what sites you visited and how much time you spend on those activities:
* RescueTime - for just about anyone
* 6th Sense - mostly for software developers
Here is another article that you might want to read comparing these two (from 2007).