Google calendar which DH has access to (it's my calendar and I add stuff to it but he will check it). Hubby has out look and a whole mess of super secure firewalls for his work calendar. A few features are available for him on his droid but not enough to make it worth it.
I also have a large monthly calendar I put up for the kids with most of our events since it's a great homeschooling tool for them in general. However I don't do well with paper calendars. My ADD means I don't go back and look at them. At least with my google calendar and the droid I get reminders so it annoys me into submission.
Herding my flock of 4 kids, all 12 and under.