We (DH and me) were using Grocery IQ but I found it to be quirky & unreliable - didn't always update between our phones quickly.
So we are now using the Cozi app - it's a calendar, grocery list, to do list. I really recommend it. You get e-mails and/or text message reminders for appointments and to do list items, and you can update it online or on your phone and everyone has the same info at the same time.
My daughter has an iPod touch (she is 9) and we even set her up with the app and she now gets reminders of things on the calendar (warning - this can also result in suddenly getting a reminder for an event like I did at midnight last night "Friday the 13th"! Apparently she felt the need to add that to the family calendar - LOL)!