Cron - Cron Calendar.

Harvest - Simple time tracking, fast online invoicing, and powerful reporting software. Simplify employee timesheets and billing. Get started for free.

KosmoTime - The to do list with super powers

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.

Vimcal - Vimcal is the world’s fastest calendar, beautifully designed for people who work remotely and live in their calendars.

Pomodone - Pomodone is the easiest way to track your workflow using Pomodoro technique, on top of your current task management service.