One thought is that it would extremely useful to be able to interact over SMS: log events, contacts, receive reminders etc.
Love the idea, keep it up!
It's too bad all of the metadata around a contact can't be kept with the contact in a portable way, and then Monica could just be an API for pointing at CardDAV and other contact servers, and a UI for interacting with them in unique ways. Personal clouds, etc.
I think Monica could be just an open API. The API is definitely something I'll work on in the next weeks, because of its potential.
Also, love your project! How do I give you money?
Edit: I'll keep an eye out for the link!