Cardhop - The Mac contacts app you'll want to use.
Reminder - A better way to keep track of your reminders 📝
Keep In touch - Keep in touch with thousands of people
Wonder - Your personal research assistant
Google Contacts - Google Contacts is Google's contact management tool that is available in its free email service Gmail, as a standalone service, and as a part of Google's business-oriented suite of web apps Google Apps.
Later Reminders - Super simple way to schedule reminders on your phone