Field Exchange between Databases

I was wondering if someone could point me to some examples of sharing data between several different Notes databases including automated updates between the calendar and todo lists with another Notes database.

Specifically, I want to create a checklist that spawns several calendar and todo items in a user’s inbox. From that point I would like the user to be able to update the todo in their own calendar and todo list and have it mail back to the original database with the completed items.

Thanks in advance.

Mark