I couldn't find a time sheet tool that I could use on my PC/Laptop when running FR campaigns (and I have enough paper as it is) so I thought I'd share this tool I made. You need .NET 4 to use it. Just open it up and run it from whereever you like, there's no installer. I used some of the info from the Wizards calendar, but needed a tracker as opposed to just a calendar.
You can download it HERE if you'd like to give it a whirl. You can set the time using the checkboxes. I usually let the time run on its own with the Start Live button and then Stop it during combat. When combat is over, I just add 10 mins and then hit Start Live up again.
Anyway, if you find it useful, great! If not, well then thats ok too 
Cheers!