PageAddict Edit
Monitor your Internet Addiction

This Free Firefox extension can give you a summary of your daily online activity, just install the PageAddict extension and surf the net, if you want to see the results, just return to PageAddict.com. There you’ll get the time spent at each site, percentages of overall time and the option to apply tags. You can even categorize different sites and restrict how much time you spend in each category per day (if you deem necessary).