Taskful - Deadlines, meet your match.
Knowee - Don't print your cards - Impress your contacts.
Streaks - The to-do list that helps you form good habits.
Sansan - Sansan provides a internal contact sharing service for companies.
ToDoBook - Turn your Facebook (& other social media) News feed into a to-do-list.
Sidekick by Hubspot - Customer insight integrated with your email tools.