This is not exactly an app but it’s a really nice site/tool, from my point of view. iCall Exchange will help you to share your calendar or make it public or private, so you can share your to-do list on line with your friends/family. You can also create a private access list, for yourself only. It’s interesting because you can sync your list with your iPhone calendar without the use of iCloud. I didn’t try this with the iPhone, instead I tested it with a windows phone and it worked just fine,! I took the iCal and created one public list and one private list…worked great!
* iCal Exchange (FREE) – http://icalexchange.com/
Don’t forget to check this out, it’s a great tool.