24 hour time
Ability to change from AM/PM to 24 hour format
Notwithstanding popular belief, many people who were born and raised in the US confuse am and pm. Lots of missed planes and servers (auto) rebooted in the middle of the day instead of in the middle of the night. In addition, sorting data when am/pm is used is a mess.
In the US, where it counts the 24H clock is used - e.g. hospitals, the military, and many IT-departments.