Chronometer is an online stopwatch with a small twist. After you press stop , it lists the task with start time, end time and a text box where you can specify the name of the task. This way you can list all the task you had been doing and ultimately export it into CSV file.
The only drawback is it will not remember your state once you reload or acess the site again. Moreover it doesn’t allow you to upload the CSV file so you can finally append more task to it. If this features can be implemented it would be much more useful. Try Chronometer