ManicTime - Track your computer usage and use collected data to accurately tag time.
TimeSnapper - TimeSnapper is an Automatic Screenshot Journal. Play back your week just like a movie.
Toggl - Toggl is an online time tracking tool. It features 1-click time tracking and helps you see where your time goes. Free and paid versions are available.
RescueTime - Time management software that shows you how you spend your time & provides tools to help you be more productive.
Qbserve - Freelance time tracking, invoicing, and productivity improvement
GtimeReport - Export your Google Calendar to Excel and Google Docs Spreadsheets.