You can use these calculators to calculate time, time zone, days till christmas, hours and minutes between two times, and more..

Time Calculator - Computing - ScottSeverance.us
Doing math with times isn't as simple as doing math with regular numbers because times use a different base. Time Calculator simplifies this problem.

Time Sheet Calculator
Calculate Hours allows you to enter times worked, like: 7:45, 11, 12:10, 3, 4, 4:30 and it will add up the time worked into a meaningful hour:minute format. You can then Sum Hours like: 6:35, 8:15, 26:15 for a total.

Days till Christmas Calculator
A simple javascript that tells you how many days left untill Christmas enhanced with the GradientLabel java applet for dynamic graphics
javascript

Time Calculator
Time Calculator is online tool that allows you to add time given in hh:mm:ss.ms (hour, minute,second,millisecond) format as well as decimal format. It could work as time converter. It could also translate time given in decimal format (hh.dec, mm.dec) to regular time format (hh:mm:ss) and vice versa. You can fast end easy calculate how many minutes makes 24 hours, how many hours are made by 1000 minutes etc.

Time Duration Calculator - How many hours and minutes between two times

Time Zone Converter – Time Difference Calculator
Find the time difference between two cities with the Time Difference Calculator. Provides time zone conversions taking into account daylight saving time (DST), local time zone and accepts present, past or future dates.