Now I had this idea which I am far too busy to follow up upon, but I'll gladly share it with you for a very modest cut of the royalties should you choose to develop it.
It's a Social App for phones (and probably tablets and PC's and whatever else...) that goes through your list of contacts - friends, and if after a month (or other user determined amount of time) you haven't contacted them - or they you, it prompts you with a reminder to call them, and if you don't within x hours or days it archives, deletes or moves the contact to an "acquaintances" group, downgrading the friendship. A hierarchical system, that keeps only the contacts you're current with, and reminding you to interact with them or lose their friendship. Optional additional features might include ranking value for friendships by how often they call you (or you them).
When you get it up and running I'll give you an address you can send royalty cheques to. I'm not greedy.