Date Calculator - Add to, Subtract From or Countdown to a Date
Date Countdown Calculator - Calculate days until event
Date to Date Calculator Download: Find out the time duration between two given dates in seconds, minutes, hours, days, weeks, months, or years, and copy the results to the clipboard
Days - Countdown & Calculator by Krzysztof Korybko
Countdown Calculator: Create a Count Down Timer for Future Event
Date Wheel date calculator for iPhone, available on the AppStore