It would be great to allow custom configuration of Time drop down in DateTimePicker control.
Since most occurrences in normal system will take place between normal business hours (7am - 6pm), it would make sense to have the time dropdown start at 7am and then go on from there so it would be:
7am 8am 9am .... 4pm 5pm 6pm ...... 12am 1am etc.
This would improve user experience by putting the most commonly selected times first in the dropdown list and reduce the scrolling the user has to perform.