I’m on Mozi
You can read more about Mozi in this NY Times article:
It lets people tell their friends about upcoming plans that may overlap. Those who join the app will see a private friend list based on their phone contacts. They get notifications if a contact plans to visit their city or attend the same event.
So, a social network for folks that already know each other. Consider signing up - with all my roaming about the US and other parts, maybe we can meet up!