In my family I am the CSO (Chief Scheduling Officer). My job is to keep track of everyone's schedules, coordinate getting people to the right place at the right time, etc.
Run your family like a business. While it may sound crazy, the only way I can get this done and not lose my mind is through my computer. My husband, the CTO (Chief Technology Officer) set up email accounts for our kids and computer log-ins on the family computer. If something gets scheduled, say soccer practice, a calendar notice is sent to all family members that shows up on their individual computer calendars. It has saved the "you didn't tell me that" arguement as everyone has the same information.
And to keep my master calendar from being totally out of control, each family member's schedule shows up in a different color. (More on color coding later...)
I currently use iCal but have used a variety of other similar calendar programs in years past. The point is get the same information to everyone who needs it as efficiently as possible.