BusyCal!

Microsoft Outlook, part of the Microsoft Office Suite (not to be confused with Microsoft Outlook Express), is a personal information manager that lets you manage your e-mail, calendar, contacts, and tasks.

Keep track of your busy schedule and share it with others using Calendar. Create separate calendars — one for home, another for school, a third for work, and so on. See all your calendars in a single window or choose to see only the calendars you want. Calendar lets you create invitations using information from Contacts, update your guest list, keep track of responses, and receive the latest status information. When you or another Mac user receives a Calendar invitation via Mail, it’s automatically added. Calendar also works with iCloud, Yahoo!, and Google. And when you use iCloud, every Calendar edit you make on your Mac automatically appears on your iPad, iPhone, and iPod touch. So no dinner dates are missed, no meeting goes unattended, and no anniversary is forgotten. »

An offline calendar without any other calendar integration. You can easily create recurring events and setup reminders, it can also display week numbers.

Android calendar-app showing the weeks of the year (week numbers), 21 languages, syncable with Google Calendar: FEATURES* intuitive navigation with smooth transitions* day, week & month calendar* 48 colors per calendar, per-event color if supported by the calendar (Android Jelly Bean with Google Calendar only)* flexible recurrences (e.g., every 3 weeks)* birthdays & anniversaries with photos from your addressbook and editing* Fullscreen widgets* custom event font size* uses Android's native calendar backend and synchronization* no battery drain* moon phases and zodiac signs for birthdays* QR barcode sharing of events* NFC sharing (if supported by the device) NEW* free* no adsTRANSLATIONSnative language support for English, Arabic, Czech, Danish, Dutch, German, Greek, Spanish, Finnish, French, Hebrew, Italian, Japanese, Korean, Polish, Portuguese, Russian, Slovak, Swedish, Turkish and Chinese with more to come »

Itsycal is a tiny calendar for your Mac menu bar. If you want, it will display your appointments and serve as a companion to the Mac Calendar app.

Calendar 366 is the perfect menu bar mate for OS X's Calendar app. Click on the icon and get an overview of your events. Click on a date and see details, or switch to the expanded view* to see all upcoming events in just a single window.

CalenGoo gives you a fast and easy way to access and change your Google Calendar (or Google Apps Calendar) with your Android device. It can either work with the built-in calendar or it can sync directly with Google.

BEAUTIFULLY DESIGNEDDigiCal’s diary planner and organizer provides a clear and beautiful overview for your events and appointments.• Conveniently switch between 7 calendar views (day, week, week agenda, month calendar, text month, year and list view in portrait and landscape mode).• The slick dark theme allows for better visibility in low-light settings and night mode.• Event keyword image matching available in all 27 languages!• 6 highly customizable widgets with different theme styles and views: (FREE: list, day, day list, day grid widgets; PREMIUM: 2 extra widgets –text month and month calendar widget)• Intuitive navigation between days, weeks and months with zoomable day and week view. »

The fast calendar for iPhone. Add an event in just two quick taps. See how full your week or day is at a glance. It works with the built-in iPhone calendar but it’s faster.

MemoCalendar.net is a light-weight and easy-to-use online calendar like a usual memo calendar on the wall. Behind every day a small note can be deposited. MemoCalendar.net is free and without registration (login) usable.

GMinder is a reminder program that waits in your system tray and alerts you when you have an upcoming Google Calendar event.

qOrganizer is a general organizer that includes a calendar with schedule,reminders,journal/notes for every day, to-do list.But provides features useful for students such as:timetable and a booklet for marks and absences.It's designed to be easy to use.