Day by Day Organizer - Time management app that combines Google Calendar and Google Tasks and enhances their features.
Remember The Milk - Remember The Milk is a task and time management application for mobile devices.
Calendar Lock PEA - Calendar Lock PEA is an encrypted desktop calendar with a day, week and month view. The shown calendars are never stored unencrypted on your disk, but exist only in the RAM. Platform-independent, Open Source, no installation or registration required.
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.
Business Calendar - Powerful and easy to use calendar app for Android including weather, widgets and tasks.
TimeCamp - Simple and robust time tracking app to help you stay on the same page with your team while working from home.