Nifty - Manage projects, work, and communications in one place.
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
ZenHub - ZenHub is how the world's best software teams work together. Trusted by NASA, Docker, and Rackspace. Start free today!
Mohalla - Mohalla is a top-rated app that lets you discover new people, join private or public chat rooms, have fun while watching videos or playing games together with other members, and build long-lasting friendships.
Intercom on Product Management - The ultimate resource for aspiring product managers
Zube - Project management for developers.