Those who work long hours in front of a computer usually worry about the amount of time that we will throughout the day on pages that are not really working because the Internet is easy to slip. In this sense it is very useful plugins as Web Time Tracker helps you know which pages you spend all your time but if your problem is more specific and has to do with Facebook, then you can serve a more simple as TimeRabbit.
TimeRabbit is a curious free application that measures the time spent on Facebook and offered statistics on it. TimeRabbit not a browser plugin, but an application that is installed on your computer and is able to monitor the activity on Facebook from common browsers likes Firefox, Chrome or Internet Explorer.
Each time you surf on Facebook using one of these browsers TimeRabbit starts counting time and when you stop browsing Facebook or the browser loses focus ceases to do so. To obtain data as accurate as possible also has ability to detect if the user is inactive and thus failing to count time.
In terms of statistics, the application will inform us about the time we spend on Facebook each day, week, month and even statistics with historical data since the program was installed. These data can be surprising, you might give clues if you spend too much time at home of Mark Zuckerberg and may even have an educational value helping parents to show their children the time actually spent on Facebook or limiting the number of hours per week that have invested in this social network to them.