There are various utilities that can keep track of your web browsing activities but none of them is much simpler than this tiny add-ons released specifically for Mozilla Firefox. Named as About:me, it is an add-ons enhancement to existing Firefox web browser so that users can easily figure out how much time have been spent in browsing activities in daily life.
allabout

Once download and install the add-ons, just restart the browsers for it to be effective. And without any setup required, users can key in “about:me” in the address field on any fresh webpage and all the information will be displayed instantly. Basically there are two statistics data namely Activity Stats and Downloads Stats that will display all these useful information in graphical view for quick glance. For the Activity Stats, users can easily figure out the most visited websites in bar chart and clicking on it will expand it into Tree view with more second level details. On top of this, it even lists down visited websites in every hour for more precise activities tracking. For Download Stats, it will show and summarize all types of files download as well as the daily downloads so that you are aware of the trend without the need to purposely keep track of them.

Although this is supposed a to be a new feature in next 3.6 version, but users can always get an earlier trial by downloading the add-ons here for immediate use.