I mentioned this above, but I think it often gets overlooked: the custom domain option is awesome, but can be especially great for families. I use the free version of Google Apps just for myself, and for $10/yr (the cost of keeping my .com address) I can have 10 different users/email addresses, all with my .com address and all with Gmail, Google Calendar, etc. It's a GREAT deal for me--as a freelancer, having a custom .com domain is much nicer to give to clients than a generic gmail address--but picture it in a family situation:
-register "yourfamily.com" (can be done via Google Apps)
-using Google Apps, you can have "email@example.com, "firstname.lastname@example.org", "email@example.com", "firstname.lastname@example.org", etc..."
-keep a family calendar that everyone can update and that everyone can see on phones, ipods, etc.
you can probably use it to make easy online photo albums for family members, etc...worth looking into if it fits your situation!