RescueTime is a great tool for monitoring what you do. It allows you to big-brother yourself. You install a background service that monitors which applications you're using and it aggregates and sorts the data in a way that helps you understand what you're spening your time doing.
This is a live chart of how I'm currently spending my month. I think most of the 'untagged' time is consumed by random web sites I'm visiting. I'm going to try to tag some of them that I regularly visit just to get a better idea of what I'm spening my time doing on the web.
I think RescueTime makes their money selling the aggregate data. The privacy statement makes it clear that they don't sell personal data but the aggregation is a goldmine for data mining.