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.
MakePlans - Online appointment booking - MakePlans
Harvest - Simple time tracking, fast online invoicing, and powerful reporting software. Simplify employee timesheets and billing. Get started for free.
Appointment Booking Calendar - With the Appointment Booking Calendar you can accept online bookings from a set of available time-slots in the calendar.
RescueTime - Time management software that shows you how you spend your time & provides tools to help you be more productive.
Dudle - Dudle is an online scheduling application, which is free and open source.