ZenHub - ZenHub is how the world's best software teams work together. Trusted by NASA, Docker, and Rackspace. Start free today!
Intercom on Product Management - The ultimate resource for aspiring product managers
Product School - The global leader in product management training
Zenkit Projects - Plan. Act. Smile.
The Product Management guide - A book on how to create and ship products that people love
Nifty - Manage projects, work, and communications in one place.