Awesome Cal - Awesome Cal is a Calendar application for your iPhone that you can take anywhere and keep close by to monitor all the upcoming birthdays, festivities, meetings, and more from a single place.
Google Calendar - Spend less time managing your day & more time enjoying it
24me - Next Generation Personal Assistant
Simple Calendar - A simple calendar with events (optional recurring and reminders), week numbers and a customizable...
Calvetica - The fast calendar for iPhone. Add an event in just two quick taps.
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.