I have been wanting something like this but for my Facebook friends. I am really bad at keeping up with people's birthdays unless it's someone I talked to at least once a week. I'd love to automate sending birthday cards like this. Or hell, even just writing on their wall with one of like 19 preset messages. Even better: an AI that determines how I talk to this particular individual (SMS, iMessage, email, Facebook Messenger, Instagram, Twitter, Snapchat, something else), and opens a pre-composed message on their birthday for me to edit and hit Send on. Obviously I need some way to blacklist certain contacts from this since I wouldn't want my partner who I live with to get a generic "Happy Birthday" while we are out to lunch or something, or an ex who I am still somehow friends with on Facebook or some such but don't actually want to talk to.
A related problem: who have I not messaged in a while? Scan my messages and tell me who is due for a "Hey, how are you doing?" message? Again, simple in principle, hard to make usable especially given that I use different apps to talk to different people.